Final answer:
The requirements for constructing a 95% confidence interval and performing a hypothesis test are met. The 95% confidence interval for the true proportion of teenage smokers is approximately 6.99% to 11.1%, indicating that the proportion may have changed from the previous 15%.
Explanation:
To ascertain if there is sufficient evidence to conclude that the percentage of teenagers who smoke has changed from 15%, we should conduct both a confidence interval analysis and a hypothesis test.
Requirements for Confidence Interval and Hypothesis Testing
Both require a random sample and a sufficiently large sample size to warrant using a normal approximation for the distribution of sample proportions. For a 95% confidence interval and hypothesis testing regarding proportions, the sample should satisfy the conditions np≥15 and n(1-p)≥15 where n is the sample size and p is the hypothesized proportion.
In this case, with a sample size of 785 and the previous proportion of 0.15, the conditions 785(0.15)≥ 15 and 785(0.85)≥ 15 are both met, satisfying the criteria to proceed with the confidence interval and hypothesis test.
95% Confidence Interval for True Proportion
To calculate the 95% confidence interval for the proportion of teenage smokers, use the formula:
Proportion = x/n
Margin of Error (ME) = z*(√[p(1-p)/n])
Lower Bound = Proportion - ME
Upper Bound = Proportion + ME
Where:
x is the number of successes in the sample (71 teenagers acknowledged smoking)
n is the sample size (785)
z is the z-score corresponding to the desired confidence level (approximately 1.96 for 95%)
Substituting in the values we get:
Proportion = 71/785 = 0.0904
ME = 1.96*√[0.0904(1-0.0904)/785] ≈ 0.0205
Lower Bound = 0.0904 - 0.0205 ≈ 0.0699
Upper Bound = 0.0904 + 0.0205 ≈ 0.111
Based on this confidence interval, we have evidence that the proportion of smokers may differ from the previous proportion of 15% as it does not include 0.15 in the interval.
For a standardized psychology examination intended for psychology majors, the historical data show that scores have a mean of 505 and a standard deviation of 170. The grading process of this year's exam has just begun. The average score of the 35 exams graded so far is 530.What is the probability that a sample of 35 exams will have a mean score of 530 or more if the exam scores follow the same distribution as in the past?
Answer:
[tex]P(\bar X>530)=1-0.808=0.192[/tex]
Step-by-step explanation:
1) Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Let X the random variable that represent the scores, and for this case we know the distribution for X is given by:
[tex]X \sim N(\mu=505,\sigma=170)[/tex]
And let [tex]\bar X[/tex] represent the sample mean, the distribution for the sample mean is given by:
[tex]\bar X \sim N(\mu,\frac{\sigma}{\sqrt{n}})[/tex]
On this case [tex]\bar X \sim N(505,\frac{170}{\sqrt{35}})[/tex]
2) Calculate the probability
We want this probability:
[tex]P(\bar X>530)=1-P(\bar X<530)[/tex]
The best way to solve this problem is using the normal standard distribution and the z score given by:
[tex]z=\frac{x-\mu}{\frac{\sigma}{\sqrt{n}}}[/tex]
If we apply this formula to our probability we got this:
[tex]P(\bar X >530)=1-P(Z<\frac{530-505}{\frac{170}{\sqrt{35}}})=1-P(Z<0.87)[/tex]
[tex]P(\bar X>530)=1-0.808=0.192[/tex]
Using the central limit theorem, the probability of a sample mean of 530 or more is calculated considering the distribution of the sample mean, which is approximately normal due to the sample size.
Explanation:To calculate the probability that a sample of 35 exams will have a mean score of 530 or more, when the population mean is 505 with a standard deviation of 170, we use the concept of the sampling distribution of the sample mean. Since the sample size is 35, which is less than 10% of all psychology majors (assuming they number in the thousands), and the population distribution is normal or the sample size is large enough (which it is in this case), we can apply the Central Limit Theorem.
This theorem states that the sampling distribution of the sample mean will be approximately normally distributed with a mean equal to the population mean (μ = 505) and a standard deviation equal to σ/√n, where σ is the population standard deviation and n is the sample size (which is √35 in this case).
For an average person, the rate of change of weight W (in pounds) with respect to height h (in inches) is given approximately by the following formula.
dW/dh=0.0018h^2
Find W(h) if W(80)equals=287.2 pounds. Also, find the weight of a person who is 5 feet, 8 inches tall.
W(h)=_______
A Person who is 5 feet, 8 inches tall weighs about _______ lbs
Answer:
[tex]W(h)=0.0006h^3-20[/tex].
A Person who is 5 feet, 8 inches tall weighs about 168.7 lbs.
Step-by-step explanation:
We know the rate of change of weight W (in pounds) with respect to height h (in inches)
[tex]\frac{dW}{dh}=0.0018h^2[/tex]
This is a separable equation. A separable equation is a first-order differential equation in which the expression for [tex]\frac{dy}{dx}[/tex] can be factored as a function of x times a function of y. In other words, it can be written in the form
[tex]\frac{dy}{dx}=g(x)f(y)[/tex]
To find W(h), we write the equation in terms of differentials and integrate both sides:[tex]\frac{dW}{dh}=0.0018h^2\\\\dW=(0.0018h^2)dh\\\\\int dW=\int (0.0018h^2)dh\\\\W=0.0006h^3+C[/tex]
To find the value of C, we use W(80) = 287.2 lbs
[tex]287.2=0.0006(80)^3+C\\0.0006\left(80\right)^3+C=287.2\\307.2+C=287.2\\307.2+C-307.2=287.2-307.2\\C=-20[/tex]
Thus,
[tex]W(h)=0.0006h^3-20[/tex]
To find the weight of a person who is 5 feet, 8 inches tall you must:Convert the 5 feet into inches
[tex]5 \:ft \:\frac{12 \:in}{1\:ft} = 60 \:in[/tex]
Add 60 in and 8 in, to find the total height of the person
h = 68 in
Substitute h = 68 in into [tex]W(h)=0.0006h^3-20[/tex] to find the weight:[tex]W(68)=0.0006(68)^3-20=168.7[/tex]
A Person who is 5 feet, 8 inches tall weighs about 168.7 lbs.
To find the weight function W(h) and the weight of a person who is 5 feet, 8 inches tall, we need to integrate the given rate of change formula and substitute the values into the equation.
Explanation:To find the weight function W(h), we need to integrate the given rate of change formula dW/dh = 0.0018[tex]h^2[/tex].
Integrating both sides, we get:
∫ dW = ∫ 0.0018[tex]h^2[/tex] dh
Integrating, we have:
W(h) = 0.0018 * (1/3) * [tex]h^3[/tex] + C
To find the value of C, we use the given information W(80) = 287.2 pounds.
Substituting the values, we have:
287.2 = 0.0018 * (1/3) * [tex]80^3[/tex] + C
Simplifying the equation, we solve for C and find:
C = 287.2 - 0.0018 * (1/3) * [tex]80^3[/tex]
Now, we can write the weight function W(h) as:
W(h) = 0.0018 * (1/3) * [tex]h^3[/tex] + (287.2 - 0.0018 * (1/3) * [tex]80^3[/tex])
To find the weight of a person who is 5 feet, 8 inches tall, we need to convert the height to inches.
5 feet is equal to 60 inches, and 8 inches is 8 inches. So, the total height is 60 + 8 = 68 inches.
Substituting the value into the weight function, we have:
W(68) = 0.0018 * (1/3) * [tex]68^3[/tex] + (287.2 - 0.0018 * (1/3) * [tex]80^3[/tex])
Simplifying the equation, we find the weight of a person who is 5 feet, 8 inches tall.
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A random variable x has a Normal distribution with an unknown mean and a standard deviation of 12. Suppose that we take a random sample of size n = 36 and find a sample mean of ¯ x = 98 . What is a 95% confidence interval for the mean of x ?
Answer: The 95% confidence interval for the mean of x is (94.08, 101.92) .
Step-by-step explanation:
We are given that ,
A random variable x has a Normal distribution with an unknown mean and a standard deviation of 12.
i.e. [tex]\sigma= 12[/tex]
Also, it is given that , Sample mean [tex]\overline{x}=98[/tex] having sample size : n= 36
For 95% confidence ,
Significance level : [tex]\alpha=1-0.95=0.05[/tex]
By using the z-value table , the two-tailed critical value for 95% Confidence interval :
[tex]z_{\alpha/2}=z_{0.025}=1.96[/tex]
We know that the confidence interval for unknown population mean[tex](\mu)[/tex] is given by :-
[tex]\overline{x}\pm z_{\alpha/2}\dfrac{\sigma}{\sqrt{n}}[/tex]
, where [tex]\overline{x}[/tex] = Sample mean
[tex]\sigma[/tex] = Population standard deviation
[tex]z_{\alpha/2}[/tex] = Critical z-value.
Substitute all the given values, then the required confidence interval will be :
[tex]98\pm (1.96)\dfrac{12}{\sqrt{36}}[/tex]
[tex]=98\pm (1.96)\dfrac{12}{6}[/tex]
[tex]=98\pm (1.96)(2)[/tex]
[tex]=98\pm 3.92=(98-3.92,\ 98+3.92)\\\\=( 94.08,\ 101.92)[/tex]
Therefore, the 95% confidence interval for the mean of x is (94.08, 101.92) .
In 2012, Gallup asked participants if they had exercised more than 30 minutes a day for three days out of the week. Suppose that random samples of 100 respondents were selected from both Vermont and Hawaii. From the survey, Vermont had 65.3% who said yes and Hawaii had 62.2% who said yes. What is the value of the sample proportion of people from Hawaii who exercised for at least 30 minutes a day 3 days a week?
Answer:
0.622
Step-by-step explanation:
According to the question,
62.2% of the respondents from Hawaii said that they had exercised more than 30 minutes a day for 3 days out of the week.
So, value of the sample proportion of people from Hawaii who exercised for at least 30 minutes a day for 3 days in a week is given by,
[tex]\frac {62.2}{100}[/tex]
= 0.622
Consider an unreliable communication channel that can successfully send a message with probability 1/2, or otherwise, the message is lost with probability 1/2. How many times do we need to transmit the message over this unreliable channel so that with probability 63/64 the message is received at least once? Explain your answer.
Hint: treat this as a Bernoulli process with a probability of success 1/2. The question is equivalent to: how many times do you have to try until you get at least one success?
Answer:
6 times we need to transmit the message over this unreliable channel so that with probability 63/64.
Step-by-step explanation:
Consider the provided information.
Let x is the number of times massage received.
It is given that the probability of successfully is 1/2.
Thus p = 1/2 and q = 1/2
We want the number of times do we need to transmit the message over this unreliable channel so that with probability 63/64 the message is received at least once.
According to the binomial distribution:
[tex]P(X=x)=\frac{n!}{r!(n-r)!}p^rq^{n-r}[/tex]
We want message is received at least once. This can be written as:
[tex]P(X\geq 1)=1-P(x=0)[/tex]
The probability of at least once is given as 63/64 we need to find the number of times we need to send the massage.
[tex]\frac{63}{64}=1-\frac{n!}{0!(n-0)!}\frac{1}{2}^0\frac{1}{2}^{n-0}[/tex]
[tex]\frac{63}{64}=1-\frac{n!}{n!}\frac{1}{2}^{n}[/tex]
[tex]\frac{63}{64}=1-\frac{1}{2}^{n}[/tex]
[tex]\frac{1}{2}^{n}=1-\frac{63}{64}[/tex]
[tex]\frac{1}{2}^{n}=\frac{1}{64}[/tex]
By comparing the value number we find that the value of n should be 6.
Hence, 6 times we need to transmit the message over this unreliable channel so that with probability 63/64.
Suppose that a one-way ANOVA is being performed to compare the means of five populations and that the sample sizes are 17 comma 15 comma 16 comma 18 comma and 11. Determine the degrees of freedom for the F-statistic.
(a) the degree of freedom of the numerator _______________________
(b) the degree of freedom of the denominator______________________
Answer:
a) [tex]df_{num}=k-1=5-1=4[/tex]
b) [tex]df_{den}=N-k=77-5=72[/tex]
Step-by-step explanation:
Analysis of variance (ANOVA) "is used to analyze the differences among group means in a sample".
The sum of squares "is the sum of the square of variation, where variation is defined as the spread between each individual value and the grand mean"
If we assume that we have [tex]p[/tex] groups and on each group from [tex]j=1,\dots,p[/tex] we have [tex]n_j[/tex] individuals on each group we can define the following formulas of variation:
[tex]SS_{total}=\sum_{j=1}^p \sum_{i=1}^{n_j} (x_{ij}-\bar x)^2 [/tex]
[tex]SS_{between}=SS_{model}=\sum_{j=1}^p n_j (\bar x_{j}-\bar x)^2 [/tex]
[tex]SS_{within}=SS_{error}=\sum_{j=1}^p \sum_{i=1}^{n_j} (x_{ij}-\bar x_j)^2 [/tex]
And we have this property
[tex]SST=SS_{between}+SS_{within}[/tex]
The degrees for the numerator are [tex]df_{num}=k-1=5-1=4[/tex], where k represent the number of groups on this case k =5.
The degrees for the denominator are [tex]df_{den}=N-k=77-5=72[/tex], where N represent the total number of people N=17+15+16+18+11=77.
And the total degrees of freedom are given by: [tex]df_{tot}=df_{num}+df_{den}=N-1=4+72=76[/tex]
Final answer:
The degrees of freedom for the F-statistic in a one-way ANOVA with five populations and sample sizes of 17, 15, 16, 18, and 11 are 4 and 72.
Explanation:
The degrees of freedom for the F-statistic in a one-way ANOVA are determined by the sample sizes of the populations being compared. In this case, the sample sizes are 17, 15, 16, 18, and 11.
The degrees of freedom for the numerator (df(num)) is equal to the number of groups being compared minus 1, which is 5-1=4.
The degrees of freedom for the denominator (df(denom)) is equal to the total number of observations minus the number of groups, which is 77-5=72. Therefore, the degrees of freedom for the F-statistic are 4 and 72.
A manufacturer of banana chips would like to know whether its bag filling machine works correctly at the 447 gram setting. It is believed that the machine is underfilling the bags. A 19 bag sample had a mean of 443 grams with a standard deviation of 21. A level of significance of 0.025 will be used. Assume the population distribution is approximately normal. Determine the decision rule for rejecting the null hypothesis. Round your answer to three decimal places.
The decision rule for rejecting the null hypothesis H₀ is
if t-statistic < -2.093.
First , let's state the null and alternative hypotheses:
Null hypothesis (H₀): The population mean weight of banana chips is 447 grams (the machine works correctly).
Alternative hypothesis (H₁): The population mean weight of banana chips is less than 447 grams (the machine is underfilling).
α = 0.025
Since this is a one-tailed test (we only care if the weight is less than 447 grams), we need to find the t-value for a single-tailed test with α = 0.025 and degrees of freedom (df) = n - 1 = 19 - 1 = 18.
We can use a t-distribution table or a statistical calculator to find this value. In most calculators, you can use the TINV function with df = 18, tails = 1, and p = 0.025. The critical value (t_α) is approximately -2.093.
Reject the null hypothesis (H₀) if the calculated t-statistic (t_stat) is less than the critical value (t_α). In other words, if the sample mean weight is significantly lower than 447 grams, we have evidence to suggest the machine is underfilling.
Reject H₀ if t_stat < -2.093.
This will require sample data (the weights of the 19 bags). Once we have that, we can calculate the t-statistic using the formula:
t_stat = (sample mean - hypothesized mean) / (standard deviation / sqrt(sample size)).
The complete question is : A manufacturer of banana chips would like to know whether its bag filling machine works correctly at the 447 gram setting. It is believed that the machine is underfilling the bags. A 19 bag sample had a mean of 443 grams with a standard deviation of 21. A level of significance of 0.025 will be used. Assume the population distribution is approximately normal. Determine the decision rule for rejecting the null hypothesis. Round your answer to three decimal places.
(1 point) You are given the parametric equations x=2t3+3t2−12t,y=2t3+3t2+1. (a) List all of the points (x,y) where the tangent line is horizontal. In entering your answer, list the points starting with the smallest value of x. If two or more points share the same value of x, list those points starting with the smallest value of y. If any blanks are unused, type an upper-case "N" in them.
Answer:
(0,1) and (13,2)
Step-by-step explanation:
We are given that parametric equations
[tex]x=2t^3+3t^2-12t[/tex]
[tex]y=2t^3+3t^2+1[/tex]
a.We have to find the points where tangent line is horizontal.
Differentiate x and y w.r.t.time
[tex]\frac{dx}{dt}=6t^2+6t-12[/tex]
[tex]\frac{dy}{dt}=6t^2+6t[/tex]
[tex]\frac{dy}{dx}=\frac{\frac{dy}{dt}}{\frac{dx}{dt}}[/tex]
Substitute the values
[tex]\frac{dy}{dx}=\frac{6t^2+6t}{6t^2+6t-12}[/tex]
We know that when tangent line is horizontal then
[tex]\frac{dy}{dx}=0[/tex]
[tex]\frac{6t^2+6t}{6t^2+6t-12}=0[/tex]
[tex]6t^2+6t=0[/tex]
[tex]t^2+t=0[/tex]
[tex]t(t+1)=0[/tex]
[tex]t=0, t+1=0[/tex]
[tex]t+1=0\implies t=-1[/tex]
Substitute the t=0 then we get
[tex]x=2(0)^3+3(0)^2-12(0)=0[/tex]
[tex]y=2(0)^3+3(0)^2+1=1[/tex]
Substitute t=-1
[tex]x=2(-1)^3+3(-1)^2-12(-1)=-2+3+12=13[/tex]
[tex]y=2(-1)^3+3(-1)^2+1=-2+3+1=2[/tex]
The points (0,1) and (13,2) where tangent line is horizontal .
To find the points where the tangent line is horizontal, we need to find the values of t that make the derivative of y with respect to x equal to 0. The points where the tangent line is horizontal are (0,1) and (20,0).
Explanation:To find the points where the tangent line is horizontal, we need to find the values of t that make the derivative of y with respect to x equal to 0. Let's start by finding the derivatives of x and y with respect to t:
[d/dt(x)]=(6t^2)+(6t)-12
[d/dt(y)]=(6t^2)+(6t)
To find the values of t that make [d/dt(y)] equal to 0, we set (6t^2)+(6t)=0. By factoring out a 6t, we get t(t+1)=0. So t=0 or t=-1. We can substitute these values of t back into the parametric equations to find the corresponding points (x,y):
t=0: x=0, y=1t=-1: x=20, y=0Therefore, the points (x,y) where the tangent line is horizontal are (0,1) and (20,0).
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A survey of 61 comma 646 people included several questions about office relationships. Of the respondents, 26.5% reported that bosses scream at employees. Use a 0.05 significance level to test the claim that more than 1 divided by 4 of people say that bosses scream at employees. How is the conclusion affected after learning that the survey is an online survey in which Internet users chose whether to respond? Identify the null hypothesis, alternative hypothesis, test statistic, P-value, conclusion about the null hypothesis, and final conclusion that addresses the original claim. Use the P-value method. Use the normal distribution as an approximation of the binomial distribution.
Answer:
H ₀ : p ≤ 0.25
H ₁: p > 0.25
Test statics value z = 12.91
Decision Rule:
Reject the value of null hypothesis
Conclusion:
If survey is online then there is sufficient evidence to claim . If the sample is voluntary response sample then conclusion is not valid.
Step-by-step explanation:
step by step explanation is shown in attachment.
A 1000-liter (L) tank contains 500 L of water with a salt concentration of 10 g/L. Water with a salt concentration of 50 g/L flows into the tank at a rate of Rin=80 L/minutes (min). The fluid mixes instantaneously and is pumped out at a specified rate Rout. Let y(t) denote the quantity of salt in the tank at time t. Assume that Rout=40L/min. (a) Set up and solve the differential equation for y(t). (b) What is the salt concentration when the tank overflows?
Final answer:
It would take roughly 22.22 hours to fill an 80,000 L swimming pool with a garden hose at a rate of 60 L/min. However, if diverting a moderate size river flowing at 5000 m³/s, it would fill the pool in approximately 0.016 seconds.
Explanation:
To estimate the time it would take to fill a private swimming pool with a capacity of 80,000 L using a garden hose delivering 60 L/min, we simply divide the total volume of the pool by the flow rate of the hose. For this calculation:
Time (min) = Total Volume (L) / Flow Rate (L/min)
Time = 80,000 L / 60 L/min = 1333.33 min
To convert minutes to hours, we divide by 60:
Time = 1333.33 min / 60 = 22.22 hours
For part (b), if you could divert a moderate size river, flowing at 5000 m³/s, into the pool, we need to convert this flow rate into liters per second (L/s) for consistency:
Flow Rate (L/s) = 5000 m³/s * 1000 L/m³
Flow Rate = 5000000 L/s
Now we can calculate the time it would take to fill the pool with this flow rate:
Time = 80,000 L / 5000000 L/s
Time = 0.016 seconds
When the moon is exactly half full, the earth, moon, and sun form a right triangle. The right angle is the angle at the moon. At that time, the angle formed by the sun earth and moon is 89.85◦ (the angle at the Earth). If the distance from the earth to the moon is 240,000 miles, estimate the distance from the earth to the sun.
The distance from earth to sun is 91,673,351.94 miles
Solution:Given that the earth, moon, and sun form a right triangle shown in figure
The figure is attached below
Point A represents moon
Point B represents sun
Point C represents earth
The right angle is the angle at the moon. This is represented by point A in right angle triangle
Given that angle at earth is 89.85 degree
Angle BCA = 89.85 degree
Distance between earth and moon = AC = 240,000 miles
Since, Right angled triangle is formed we can use trigonometric identities
[tex]\cos \theta=\frac{B a s e}{\text {Hypotenuse}}[/tex]
The angle θ means angle created on earth
i.e. angle BCA = θ = 89.85 degree
[tex]\cos \left(89.85^{\circ}\right)=\frac{A C}{B C}[/tex]
Let BC = d, which is the distance between Earth and the sun
[tex]\mathrm{D}=\frac{240,000}{\cos (89.85)}=91,673,351.94 \mathrm{miles}[/tex]
So the distance from earth to sun is 91,673,351.94 miles
To estimate the distance from the Earth to the Sun when the Moon is exactly half full and the Earth, Moon, and Sun form a right triangle, we can use the concept of similar triangles. By setting up a proportion and using the tangent function, we can calculate that the estimated distance is approximately 243,480,000 miles.
Explanation:To estimate the distance from the Earth to the Sun, we can use the concept of similar triangles. When the Moon is exactly half full, the Earth, Moon, and Sun form a right triangle, with the right angle at the Moon. We know that the angle formed by the Sun, Earth, and Moon is 89.85 degrees.
We can use this information to set up a proportion between the distance from the Earth to the Moon and the distance from the Earth to the Sun. Let x be the distance from the Earth to the Sun. We can use the tangent function to find x:
Tan(89.85) = (240,000 miles) / x
Solving for x, we get:
x = (240,000 miles) / Tan(89.85)
Using a calculator, we find that x is approximately 243,480,000 miles.
A federal agency responsible for enforcing laws governing weights and measures routinely inspects packages to determine whether the weight of the contents is at least as great as that advertised on the package. A random sample of 18 containers whose packaging states that the contents weigh 8 ounces was drawn. The contents were weighed, and the results follow. Can we conclude at the 1% significance level that on average the containers are mislabeled?
Answer: We can conclude that the average containers are mislabelled.
Step-by-step explanation:
From the question, the significant level of 0.01 or 1% given is less than 0.05 or 5%. So we say it is significant.
Rounded to the nearest hundredth, what is the positive solution to the quadratic equation 0=2x2+3x-8?
Quadratic formula: x =StartFraction negative b plus or minus StartRoot b squared minus 4 a c EndRoot Over 2 a EndFraction
A. 1.39
B. 2.00
C. 2.89
D. 3.50
Answer:
Step-by-step explanation:
The given quadratic equation is
2x^2+3x-8 = 0
To find the roots of the equation. We will apply the general formula for quadratic equations
x = -b ± √b^2 - 4ac]/2a
from the equation,
a = 2
b = 3
c = -8
It becomes
x = [- 3 ± √3^2 - 4(2 × -8)]/2×2
x = - 3 ± √9 - 4(- 16)]/2×2
x = [- 3 ± √9 + 64]/2×2
x = [- 3 ± √73]/4
x = [- 3 ± 8.544]/4
x = (-3 + 8.544) /4 or x = (-3 - 8.544) / 4
x = 5.544/4 or - 11.544/4
x = 1.386 or x = - 2.886
The positive solution is 1.39 rounded up to the nearest hundredth
Answer:
its a. 1.39
Step-by-step explanation:
A firm that stocks lightbulbs gathers the following information: Demand = 19,500 units per year, Ordering cost = $25 per order, Holding cost = $4 per unit per year. The firm wants to calculate the: a) EOQ for the lightbulbs. b) Annual holding costs for the lightbulbs. c) Annual ordering costs for the lightbulbs.
Answer:
Step-by-step explanation:
Demand = 19,500 units per year (D)
Ordering cost = $25 per order (O)
Holding cost = $4 per unit per year (C)
a) [tex]EOQ=\sqrt{ \frac{2\times D\times O}{C}}[/tex]
[tex]EOQ=\sqrt{ \frac{2\times 19,500\times 25}{4}}[/tex]
= [tex]\sqrt{\frac{975000}{4}}[/tex]
= [tex]\sqrt{243,750}[/tex]
= 493.71044 ≈ 494
b) Annual holding cost = [tex]4\times(\frac{Q}{2})[/tex]
= [tex]4\times(\frac{494}{2})[/tex]
= 4 × 247
= 988
c) Annual ordering cost = [tex]O\times(\frac{D}{Q} )[/tex]
= [tex]25\times(\frac{19,500}{494} )[/tex]
= 25 × 39.47
= 986.75
AOQ = 494
Annual holding cost = 988
Annual ordering cost = 986.75
The local orchestra has been invited to play at a festival. There are 111 members of the orchestra and 6 are licensed to drive large multi-passenger vehicles. Busses hold 25 people but are much more expensive to rent. Passenger vans hold 12 people. make a system of equations to find the smallest number of busses the orchestra can rent. Let x= the number of busses and y= the number of vans make an equation representing the number of vehicles needed. __________ make an equation representing the total number of seats in vehicles for the orchestra members. __________ Solve the system of equations. How many busses does the orchestra need to rent? ____________ How many 12-passenger vans does the orchestra need to rent? ____________
- Make an equation representing the number of vehicles needed.
We have six drivers so
x + y ≤ 6
That's not really an equation; it's an inequality. We want to use all our drivers so we can use the small vans, so
x + y = 6
- Make an equation representing the total number of seats in vehicles for the orchestra members.
s = 25x + 12y
That's how many seats total; it has to be at least 111 so again an inequality,
25x + 12y ≥ 111
We solve it like a system of equations.
x + y = 6
y = 6 - x
111 = 25x + 12y = 25x + 12(6-x)
111 = 25x + 72 - 12x
111 - 72 = 13 x
39 = 13 x
x = 3
Look at that, it worked out exactly. It didn't have to.
y = 6 - x = 3
Answer: 3 buses, 3 vans
Using a System of equations, the number of buses and vans required are 3 respectively.
Using the system of equations :
Total number of buses :
b + v ≤ 6 - - - - (1)Total number of passengers :
25b + 12v ≥ 111 - - - - (2)From (1)
b = 6 - v - - - - - (3)Substitute (3) into (2)
25(6-v) + 12v = 111
150 - 25v + 12v = 111
-13v = 111 - 150
-13v = - 39
v = 39/13
v = 3
From (3)
b = 6 - 3
b = 3
Hence, the number of vans and buses required are 3 and 3 respectively.
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Based on the following information, what is the standard deviation of returns? State of Economy Probability of State of Economy Rate of Return if State Occurs Recession .22 − .112 Normal .25 .127 Boom .53 .237
The standard deviation of returns is 2.82% by calculating expected value, variance and standard deviation.
Given that:
State of Economy Probability Rate of Return if State Occurs
Recession 0.22 -0.9
Normal 0.47 0.105
Boom 0.31 0.215
To calculate the standard deviation of returns, by using the formula:
Standard Deviation = [tex]\sqrt{}[/tex][Σ (Probability * (Rate of Return - Expected Return[tex])^2[/tex])]
Step 1: calculate the Expected Return: Multiply each rate of return by its corresponding probability and sum the results:
E = Σ(Rate of Return* Probability )
Plugging the given data gives:
E = (0.22 * -0.9) + (0.47 * 0.105) + (0.31 * 0.215)
On multiplication gives
E = 0.0225 - 0.04935 + 0.06665
On solving gives:
E = 0.0398.
Step 2: Calculate the Variance: For each rate of return, subtract the expected return, square the result, multiply by its corresponding probability, and sum the results:
Variance ( V) = Σ (Probability * (Rate of Return - Expected Return[tex])^2[/tex]
Plugging the given data gives:
[tex]V = [(0.22 * (-0.9 - 0.0398)^2) + (0.47 * (0.105 - 0.0398)^2) + (0.31 * (0.215 - 0.0398)^2)][/tex]
On squaring and solving gives:
[tex]V = [0.0225 + 0.02741 + 0.0412][/tex]
On adding gives:
[tex]V = 0.09111.[/tex]
Step3: Find the square root of the variance to get the Standard Deviation:
[tex]\sigma = \sqrt V[/tex]
Plugging the given data gives:
[tex]\sigma = \sqrt{0.09111 }[/tex]
On taking square root gives:
[tex]\sigma \approx 0.282[/tex] or 2.82%.
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Question:
Based on the following information, what is the standard deviation of returns?
State of Economy Probability Rate of Return if State Occurs
Recession 0.22 -0.9
Normal 0.47 0.105
Boom 0.31 0.215
To calculate the standard deviation of returns, follow these steps: 1) Calculate the expected return for each state by multiplying the probability of the state occurring by the rate of return. 2) Calculate the squared difference between each state's return and the expected return. 3) Multiply each squared difference by the probability of the state occurring. 4) Sum up all the values obtained in step 3. 5) Take the square root of the sum obtained in step 4.
Explanation:To calculate the standard deviation of returns, we need to follow these steps:
Calculate the expected return for each state of the economy by multiplying the probability of the state occurring by the rate of return for that state.Calculate the squared difference between each state's return and the expected return.Multiply each squared difference by the probability of the state occurring.Sum up all the values obtained in step 3.Take the square root of the sum obtained in step 4.Using the given information:
Expected return for Recession: (.22)*(-.112) = -0.02464Expected return for Normal: (.25)*(0.127) = 0.03175Expected return for Boom: (.53)*(0.237) = 0.12561Next, we calculate the squared difference between each state's return and the expected return:
For Recession: (-0.112 - (-0.02464))^2 = 0.005019024For Normal: (0.127 - 0.03175)^2 = 0.00718400625For Boom: (0.237 - 0.12561)^2 = 0.0122397638Then, we multiply each squared difference by the probability of the state occurring:
For Recession: 0.005019024 * 0.22 = 0.00110478528For Normal: 0.00718400625 * 0.25 = 0.0017960015625For Boom: 0.0122397638 * 0.53 = 0.006496061714Finally, we sum up all the values obtained:
0.00110478528 + 0.0017960015625 + 0.006496061714 = 0.0093968483025And take the square root of the sum:
Square root of 0.0093968483025 = 0.096919769Therefore, the standard deviation of returns is approximately 0.0969.
Two accounting professors decided to compare the variance of their grading procedures. To accomplish this, they each graded the same 10 exams, with the following results: Mean Grade Standard Deviation Professor 1 79.3 22.4 Professor 2 82.1 12.0 At the 10% level of significance, what is the decision regarding the null hypothesis? A) Reject the null hypothesis and conclude the variances are different. B) Fail to reject the null hypothesis and conclude no significant difference in the variances. C) Reject the null hypothesis and conclude the variances are the same. D) Fail to reject the null hypothesis and conclude the variances are the same.
Without the exact F-statistic and p-value, it is not possible to definitively choose between rejecting or failing to reject the null hypothesis. The decision would depend on whether the calculated p-value is less than the level of significance (0.10).
Explanation:To determine whether there is a significant difference in the variance of grading procedures between two professors, we need to conduct an F-test for variance. The null hypothesis (H0) would be that there is no significant difference in the variances of grading, while the alternative hypothesis (H1) would be that there is a significant difference in the variances.
Using the data provided:
Professor 1: Mean grade = 79.3, Standard Deviation = 22.4Professor 2: Mean grade = 82.1, Standard Deviation = 12.0The F-statistic is calculated by dividing the variance of the set with the larger variance (squared standard deviation) by the variance of the set with the smaller variance, which means:
F = (22.4)^2 / (12.0)^2
However, the exact F value is not provided in the data, nor is the p-value. To make the decision, we would compare the p-value to the level of significance (
0.10). If the p-value is less than 0.10, we would reject the null hypothesis, indicating that there is a significant difference between the variances. If the p-value is greater than 0.10, we would fail to reject the null hypothesis, indicating there is no significant difference in variances.
Based on the options provided in the question, without the exact p-value or F-statistic, we cannot provide the correct answer. Thus, the answer would depend on the calculated p-value from the F-statistic. The options, therefore, are between A (rejecting the H0) or B (failing to reject the H0), and an exact answer requires additional information from an F-test.
You invested $19,000 in two accounts paying 5% and 9% annual interest, respectively. If the total interest earned for the year was
$1390, how much was invested at each rate?
Answer:
0.08x + 0.09y = 1700, where x is the amount that has 8% interest
y is the amount that has 9% interest
-------equation (1)
x+y = 19000
x = 19000 - y , -------equation (2)
substitute (2) into (1):
0.08(19000 - y) + 0.09y = 1700
1520-0.08y+0.09y = 1700
so, y = 18000
x = 19000-y=1000
(1000, 18000) is the answer
Just to let you know I’m in 7th grade
The problem can be solved by creating a system of linear equations that represent the conditions given in the problem. Solve this system of equations to determine the amounts invested in each of the two accounts.
Explanation:This is a problem of algebra, specifically a type of word problem called a system of linear equations. You have a total of $19,000 invested across two accounts. Let's denote the amount invested at 5% as x and the amount invested at 9% as y. So, we can write two equations:
x + y = $19,000 (since the total money invested is $19,000), and 0.05x + 0.09y = $1,390 (since the total interest is $1,390)The next step is to solve this system of equations. Multiply the first equation by 0.05 (so it matches 5% in the second equation), then subtract the resulting equation from the second equation to eliminate x. By doing this, you find the value for y (money in the 9% account). Once you have the value for y, you can substitute it into the first equation to find the value for x (money in the 5% account).
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Which triangle congruence postulate proves these two triangle are congruent?
A. AAS
B. HL
C. SAS
D. ASA
Please answer this
Answer:
A. AAS
Step-by-step explanation:
The vertical angles are congruent, the adjacent marked angles are congruent, and the marked sides on the far side of both angles are congruent. This geometry matches the conditions for Angle-Angle-Side (AAS) congruence.
Find the absolute extrema of f(x) = e^{x^2+2x}f ( x ) = e x 2 + 2 x on the interval [-2,2][ − 2 , 2 ] first and then use the comparison property to find the lower and upper bounds for I = \displaystyle \int_{-2}^{2} f(x) \, dxI = ∫ − 2 2 f ( x ) d x.
[tex]f(x)=e^{x^2+2x}\implies f'(x)=2(x+1)e^{x^2+2x}[/tex]
[tex]f[/tex] has critical points where the derivative is 0:
[tex]2(x+1)e^{x^2+2x}=0\implies x+1=0\implies x=-1[/tex]
The second derivative is
[tex]f''(x)=2e^{x^2+2x}+4(x+1)^2e^{x^2+2x}=2(2x^2+4x+3)e^{x^2+2x}[/tex]
and [tex]f''(-1)=\frac2e>0[/tex], which indicates a local minimum at [tex]x=-1[/tex] with a value of [tex]f(-1)=\frac1e[/tex].
At the endpoints of [-2, 2], we have [tex]f(-2)=1[/tex] and [tex]f(2)=e^8[/tex], so that [tex]f[/tex] has an absolute minimum of [tex]\frac1e[/tex] and an absolute maximum of [tex]e^8[/tex] on [-2, 2].
So we have
[tex]\dfrac1e\le f(x)\le e^8[/tex]
[tex]\implies\displaystyle\int_{-2}^2\frac{\mathrm dx}e\le\int_{-2}^2f(x)\,\mathrm dx\le\int_{-2}^2e^8\,\mathrm dx[/tex]
[tex]\implies\boxed{\displaystyle\frac4e\le\int_{-2}^2f(x)\,\mathrm dx\le4e^8}[/tex]
There are 20 members of a basketball team.
(a) The coach must select 12 players to travel to an away game. How many ways are there to select the players who will travel?
(b) From the 12 players who will travel, the coach must select her starting line-up. She will select a player for each of the five positions: center, power forward, small forward, shooting guard and point guard. How many ways are there for her to select the starting line-up?
(c) From the 12 players who will travel, the coach must select her starting line-up. She will select a player for each of the five positions: center, power forward, small forward, shooting guard and point guard. However, there are only three of the 12 players who can play center. Otherwise, there are no restrictions. How many ways are there for her to select the starting line-up?
There are 125,970 ways to select the players who will travel to an away game. There are 79,833,600 ways to select the starting line-up. With a restriction on the center position, there are 12 ways to select the starting line-up.
Explanation:(a) The coach must select 12 players to travel to an away game:
There are 20 members on the basketball team, and the coach needs to select 12 players to travel. This is a combination problem, since the order doesn't matter. The formula for calculating combinations is: nCr = n! / (r! * (n-r)!), where n is the total number of players and r is the number of players to be selected.
Using this formula, we can calculate the number of ways to select the traveling players: 20C12 = 20! / (12! * (20-12)!) = 125,970 ways.
(b) The coach must select her starting line-up:
There are 12 players who will travel, and the coach needs to select 5 players for the starting line-up. This is a permutation problem, since the order does matter. The formula for calculating permutations is: nPr = n! / (n-r)!, where n is the total number of players and r is the number of players to be selected.
Using this formula, we can calculate the number of ways to select the starting line-up: 12P5 = 12! / (12-5)! = 12! / 7! = 79,833,600 ways.
(c) The coach must select her starting line-up, with a restriction on the center position:
There are 12 players who will travel, and only 3 players who can play center. The remaining 4 positions have no restrictions. We can calculate the number of ways to select the starting line-up by first selecting the center player (3 ways), and then selecting the players for the other positions (4P4 = 4 ways).
Therefore, the total number of ways to select the starting line-up with the restriction on the center position is: 3 * 4 = 12 ways.
The ant hill is 19.5 cm tall. How many mm tall is the ant hill
Answer:
195 mm
Step-by-step explanation:
There are 10 mm in one cm. This is due to metric prefix rules
An engineer is comparing voltages for two types of batteries (K and Q) using a sample of 37 type K batteries and a sample of 58 type Q batteries. The mean voltage is measured as 8.54 for the type K batteries with a standard deviation of 0.225, and the mean voltage is 8.69 for type Q batteries with a standard deviation of 0.725. Conduct a hypothesis test for the conjecture that the mean voltage for these two types of batteries is different. Let μ1 be the true mean voltage for type K batteries and μ2 be the true mean voltage for type Q batteries. Use a 0.10.1 level of significance.
Step 1 of 4: State the null and alternative hypotheses for the test.
Step 2 of 4: Compute the value of the test statistic. Round your answer to two decimal places.
Step 3 of 4: Determine the decision rule for rejecting the null hypothesis H0. Round the numerical portion of your answer to two decimal places.
Step 4 of 4: Make the decision for the hypothesis test.
Answer:
Step-by-step explanation:
Hello!
You want to test two samples of batteries to see is the mean voltage of these battery types are different.
Sample 1 (type K)
n₁= 37
sample mean x₁[bar]= 8.54
standard deviation S₁= 0.225
Sample 2 (Type Q)
n₂= 58
sample mean x₂[bar]= 8.69
standard deviation S₂= 0.725
1. The test hypothesis are:
H₀: μ₁ = μ₂
H₁: μ₁ ≠ μ₂
2. I'll apply the Central Limit Theorem and approximate the distribution of the sample means to normal so that I can use an approximate Z statistic for this test.
Z: (x₁[bar] - x₂[bar]) - (μ₁ - μ₂) ≈ N(0;1)
√ (S₁²/n₁) + (S₂²/n₂)
[tex]Z_{H0}[/tex]= (8.54 - 8.69) / [√ (0.225²/37) + (0.725²/58)]
[tex]Z_{H0}[/tex]= -1.468 ≅ -1.47
3. This is a two tailed test, so you'll have two critical values
[tex]Z_{\alpha/2} = Z_{0.025} = - 1.96[/tex]
[tex]Z_{1 - \alpha/2} = Z_{0.975} = 1.96[/tex]
You'll reject the null hypothesis if [tex]Z_{H0}[/tex] ≤ -1.96 or if [tex]Z_{H0}[/tex] ≥ 1.96
You'll not reject the null hypothesis if -1.96 < [tex]Z_{H0}[/tex] < 1.96
4.
Since the value [tex]Z_{H0}[/tex] = -1.47 is in the acceptance region, the decision is to not reject the null hypothesis.
I hope it helps!
Answer:
Step-by-step explanation:
Write the quadratic equation whose roots are -2 and 1, and whose leading coefficient is 4 .
Answer: the equation is
4x^2 + 4x - 12
Step-by-step explanation:
A quadratic equation is an equation in which the highest power of the unknown is 2.
The general form of a quadratic equation is expressed as
ax^2 + bx + c
Where
a is the leading coefficient
c is a constant
Assuming we want to write the quadratic equation in x, from the information given, the roots which are given are -2 and 1 and the leading coefficient is 4.
Therefore, the linear factors of the quadratic equation will be (x+2) and (x-1)
the equation becomes
(x+2)(x-1)
= x^2 - x +2x - 3
= x^2 + x - 3
Given a leading coefficient of 4, we will multiply the quadratic expression by 4. It becomes
4(x^2 + x - 3)
= 4x^2 + 4x - 12
Final answer:
The quadratic equation with roots -2 and 1 and a leading coefficient of 4 is 4x^2 - 12x + 8 = 0.
Explanation:
To write a quadratic equation with roots -2 and 1 and a leading coefficient of 4, we need to use the fact that if α and β are roots of a quadratic equation, then the equation can be expressed in the form:
a(x - α)(x - β) = 0
Here, α is -2 and β is 1, and the leading coefficient, a, is 4. Therefore, we can write:
4(x + 2)(x - 1) = 0
Multiplying it out, we have:
4(x2 - 1x - 2x + 2) = 0
Combining like terms, we get:
4x2 - 12x + 8 = 0, which is the desired quadratic equation.
In a recent poll of 750 randomly selected adults, 589 said that it is morally wrong to not report all income on tax returns. Use a 0.05 significance level to test the claim that 70% of adults say that it is morally wrong to not report all income on tax returns. Identify the null hypothesis, alternative hypothesis, test statistic, P-value, conclusion about the null hypothesis, and final conclusion that addresses the original claim. Use the P-value method. Use the normal distribution as an approximation of the binomial distribution.
Answer:
z= 5.08
The p value obtained was a very low value and using the significance level given [tex]\alpha=0.05[/tex] we have [tex]p_v<\alpha[/tex] so we can conclude that we have enough evidence to reject the null hypothesis, and we can said that at 5% of significance the proportion of adults who say's that it is morally wrong to not report all income on tax returns differs from 0.7 or 70% .
Step-by-step explanation:
1) Data given and notation
n=750 represent the random sample taken
X=589 represent the adults that said that it is morally wrong to not report all income on tax returns
[tex]\hat p=\frac{589}{750}=0.785[/tex] estimated proportion of adults that said that it is morally wrong to not report all income on tax returns
[tex]p_o=0.7[/tex] is the value that we want to test
[tex]\alpha=0.05[/tex] represent the significance level
Confidence=95% or 0.95
z would represent the statistic (variable of interest)
pv represent the p value (variable of interest)
2) Concepts and formulas to use
We need to conduct a hypothesis in order to test the claim that 70% of adults say that it is morally wrong to not report all income on tax returns.:
Null hypothesis:[tex]p=0.7[/tex]
Alternative hypothesis:[tex]p \neq 0.7[/tex]
When we conduct a proportion test we need to use the z statisitc, and the is given by:
[tex]z=\frac{\hat p -p_o}{\sqrt{\frac{p_o (1-p_o)}{n}}}[/tex] (1)
The One-Sample Proportion Test is used to assess whether a population proportion [tex]\hat p[/tex] is significantly different from a hypothesized value [tex]p_o[/tex].
3) Calculate the statistic
Since we have all the info requires we can replace in formula (1) like this:
[tex]z=\frac{0.785 -0.7}{\sqrt{\frac{0.7(1-0.7)}{750}}}=5.08[/tex]
4) Statistical decision
It's important to refresh the p value method or p value approach . "This method is about determining "likely" or "unlikely" by determining the probability assuming the null hypothesis were true of observing a more extreme test statistic in the direction of the alternative hypothesis than the one observed". Or in other words is just a method to have an statistical decision to fail to reject or reject the null hypothesis.
The significance level provided [tex]\alpha=0.05[/tex]. The next step would be calculate the p value for this test.
Since is a bilateral test the p value would be:
[tex]p_v =2*P(z>5.08)=0.000000377[/tex]
So the p value obtained was a very low value and using the significance level given [tex]\alpha=0.05[/tex] we have [tex]p_v<\alpha[/tex] so we can conclude that we have enough evidence to reject the null hypothesis, and we can said that at 5% of significance the proportion of adults who say's that it is morally wrong to not report all income on tax returns differs from 0.7 or 70% .
Juan only paid $10 for his new letter. He got 25% discount what was the original price of the sweater?
Answer:
$12.50
Step-by-step explanation:
so Juan got his sweater at a 25% discount. So we woukd find 25% of 10 and then add it to $10
Answer:
Step-by-step explanation:
Juan only paid $10 for his new Sweater. He got a 25% discount
Let the original price of the sweater be $x. If he gets s 35% discount, it means that the price which she paid was lower than the original price.
Discount of 25% on the original price = 25/100 × x = 0.25x
The amount of money that Juan paid is the original price minus the discount of 25%. It becomes
x - 0.25x = 0.75x
Amount paid = $10. Therefore
0.75x = 10
x = 10/0.75 = $13.33
PLEASE HELP
Answer all three of the questions below.
1. Write an equivalent expression to 2 + 3 + 5 + 6 by combining like terms.
2. Find the sum of (8a – 2b - 4) and (3b − 5).
3.Write the expression in standard form: 4(2a) + 7(−4b) + (3 ∙ c ∙ 5).
Answer:
a)[tex]2 + 3 + 5 + 6 = 16[/tex]
b)[tex]8a + b-9[/tex]
c)[tex]8a - 28b + 15c[/tex]
Step-by-step explanation:
We are given the following in the question:
1. Equivalent expression
[tex]2 + 3 + 5 + 6[/tex]
Since all the terms are like terms, we can write,
[tex]2 + 3 + 5 + 6 = 16[/tex]
2. Sum of given expression
[tex](8a - 2b - 4) \text{ and } (3b - 5)\\ (8a - 2b - 4) + (3b -5)\\= 8a -2b -4 + 3b -5\\\text{Collecting the like terms}\\8a + (-2b+3b) + (-4-5)\\= 8a + b-9[/tex]
3. Standard form of the expression
[tex]4(2a) + 7(-4b) + (3 \times c \times 5)\\=(8a) + (-28b) + (15c)\\=8a - 28b + 15c[/tex]
which is the required standard form of the given expression.
Suppose a compact disk (CD) you just purchased has 1515 tracks. After listening to the CD, you decide that you like 66 of the songs. The random feature on your CD player will play each of the 1515 songs once in a random order. Find the probability that among the first 55 songs played (a) you like 2 of them; (b) you like 3 of them; (c) you like all 55 of them.
Answer:
(A) 0.4196
(B) 0.2398
(C) 0.0020
Step-by-step explanation:
Given,
Total songs = 15,
Liked songs = 6,
So, not liked songs = 15 - 6 = 9
If any 5 songs are played,
Then the total number of ways = [tex]^{15}C_5[/tex]
(A) Number of ways of choosing 2 liked songs = [tex]^6C_2\times ^9C_3[/tex]
Since,
[tex]\text{Probability}=\frac{\text{Favourable outcomes}}{\text{Total outcomes}}[/tex]
Thus, the probability of choosing 3 females and 2 males = [tex]\frac{ ^6C_2\times ^9C_3}{^{15}C_5}[/tex]
[tex]=\frac{\frac{6!}{2!4!}\times \frac{9!}{3!6!}}{\frac{15!}{10!5!}}[/tex]
= 0.4196
Similarly,
(B)
The probability of choosing 3 liked songs = [tex]\frac{ ^6C_3\times ^9C_2}{^{15}C_5}[/tex]
[tex]=\frac{\frac{6!}{3!3!}\times \frac{9!}{2!7!}}{\frac{15!}{10!5!}}[/tex]
= 0.2398
(C)
The probability of choosing 5 liked songs = [tex]\frac{ ^6C_5\times ^9C_0}{^{15}C_5}[/tex]
[tex]=\frac{\frac{6!}{5!1!}}{\frac{15!}{5!10!}}[/tex]
≈ 0.0020
For a rectangular cube with a square base, suppose that it costs $3/cm^2 for the material used on the side and $6/cm^2 for the material used for the top lid and the base. Assuming that the volume of this container is 54 cm^3 , what is the side length of the cube with the smallest cost?
Answer:
The sides of the container should be 3 cm and height should be 6 cm to minimize the cost
Step-by-step explanation:
Data provided in the question:
costs for the material used on the side = $3/cm²
costs for the material used for the top lid and the base = $6/cm²
Volume of the container = 54 cm³
Now,
let the side of the base be 'x' and the height of the box be 'y'
Thus,
x × x × y = 54 cm³
or
x²y = 54
or
y = [tex]\frac{54}{x^2}[/tex] ............(1)
Now,
The total cost of material, C
C = $3 × ( 4 side area of the box ) + $6 × (Area of the top and bottom)
or
C = ( $3 × 4xy ) + ( $6 × (x²) )
substituting the value of y in the above equation, we get
C = [tex]3x\times4\times\frac{54}{x^2}+2\times6x^2[/tex]
or
C = [tex]\frac{648}{x}+12x^2[/tex]
Differentiating with respect to x and putting it equals to zero to find the point of maxima of minima
thus,
C' = [tex]-\frac{648}{x^2}+2\times12x[/tex] = 0
or
[tex]2\times12x=\frac{648}{x^2}[/tex]
or
24x³ = 648
or
x = 3 cm
also,
C'' = [tex]+\frac{2\times648}{x^3}+2\times12[/tex]
or
C''(3) = [tex]+\frac{2\times648}{3^3}+2\times12[/tex] > 0
Hence,
x = 3 cm is point of minima
Therefore,
y = [tex]\frac{54}{x^2}[/tex] [from 1]
or
y = [tex]\frac{54}{3^2}[/tex]
or
y = 6 cm
Hence,
The sides of the container should be 3 cm and height should be 6 cm to minimize the cost
Find the flux of the following vector fields across the given surface with the specified orientation. You may use either an explicit or parametric description of the surface.
44. F=〈x,y,z〉across the slanted face of the tetrahedron z=10−2x−5y in the first octant; normal vectors point upward.
The tetrahedron passes through the intercepts (5, 0, 0), (0, 2, 0), and (0, 0, 10). Parameterize the surface (call it [tex]\Sigma[/tex]) by
[tex]\vec r(u,v)=(1-v)\langle5,0,0\rangle+v\left((1-u)\langle0,2,0\rangle+u\langle0,0,10\rangle\right)[/tex]
[tex]\vec r(u,v)=\langle5(1-v),2(1-u)v,10uv\rangle[/tex]
with [tex]0\le u\le1[/tex] and [tex]0\le v\le1[/tex]. Take the normal vector to [tex]\Sigma[/tex] to be
[tex]\vec r_v\times\vec r_u=\langle20v,50v,10v\rangle[/tex]
Then the flux of [tex]\vec F(x,y,z)=\langle x,y,z\rangle[/tex] across [tex]\Sigma[/tex] is
[tex]\displaystyle\iint_\Sigma\vec F\cdot\mathrm d\vec S=\int_0^1\int_0^1\langle5(1-v),2(1-u)v,10uv\rangle\cdot\langle20v,50v,10v\rangle\,\mathrm du\,\mathrm dv[/tex]
[tex]=\displaystyle\int_0^1\int_0^1100v\,\mathrm du\,\mathrm dv=\boxed{50}[/tex]