Answer:
Correct option: (b).
Step-by-step explanation:
Effect size (η) is a statistical measure that determines the strength of the association (numerically) between two variables. For example, if we have data on the weight of male and female candidates and we realize that, on average, males are heavier than females, the difference between the weight of male and the weight of female candidates is known as the effect size.
The larger the effect size, the larger the weight difference between male and female will be.
Statistic effect size helps us in analyzing if the difference is factual or if it is affected by a change of factors.
In hypothesis testing, effect size, power, sample size, and critical significance level are related to each other.
The effect size formula for a hypothesis test of mean difference is:
[tex]\eta =\frac{\bar x_{1}-\bar x_{2}}{\sqrt{s^{2}}}[/tex]
The denominator s² is combined sample variance.
[tex]s^{2}=\frac{n_{1}s_{1}^{2}+n_{2}s_{2}^{2}}{n_{1}+n_{2}-2}[/tex]
The effect size is affected by two components:
Sample mean differenceSample variance.As the sample mean difference is directly proportional to the effect size, on increasing the sample mean difference value the effect size will also increase.
Ans the sample variance is inversely proportional to the the effect size, on decreasing the sample variance value the effect size will increase and vice-versa.
Thus, the correct option is (b).
A trade magazine routinely checks the drive-through service times of fast-food restaurants. Upper A A 90 90% confidence interval that results from examining 691 691 customers in one fast-food chain's drive-through has a lower bound of 161.9 161.9 seconds and an upper bound of 165.5 165.5 seconds. What does this mean? Choose the correct answer below. A. One can be 90 90% confident that the mean drive-through service time of this fast-food chain is between 161.9 161.9 seconds and 165.5 165.5 seconds. B. One can be 90 90% confident that the mean drive-through service time of this fast-food chain is 163.7 163.7 seconds. C. There is a a 90 90% probability that the mean drive-through service time of this fast-food chain is between 161.9 161.9 seconds and 165.5 165.5 seconds. D. The mean drive-through service time of this fast-food chain is 163.7 163.7 seconds 90 90% of the time.
Answer:
Step-by-step explanation:
Confidence interval gives possible estimate (range of values) that could contain the population proportion. Confidence level does not not mean probability. It only tells how confident we are that that the population proportion lies within the confidence interval.
Since we were told that the confidence interval has a lower bound of 161.9 seconds and an upper bound of 165.5 seconds, therefore, the correct option for the given situation is
A. One can be 90% confident that the mean drive-through service time of this fast-food chain is between 161.9 seconds and 165.5 seconds.
The correct interpretation of the 90% confidence interval for the fast-food chain's drive-through service times is that it likely contains the true mean service time (A. One can be 90% confident that the mean drive-through service time is between 161.9 seconds and 165.5 seconds).
The correct answer to the question is A. One can be 90% confident that the mean drive-through service time of this fast-food chain is between 161.9 seconds and 165.5 seconds. This statement is a proper interpretation of a confidence interval in statistics. Confidence intervals provide a range of values, derived from the data sample, that likely contain the population parameter of interest. In this case, the parameter of interest is the mean drive-through service time. Option B is incorrect because it overly simplifies the range into a single value. Option C is misleading because it attributes a probability to the mean's location, which is not accurate in the context of confidence intervals. Lastly, option D incorrectly suggests that the mean service time falls within a specific range 90% of the time, rather than conveying the level of confidence in the interval containing the true mean.
Factor completely. − 3 x 2 + 6 x + 9 = −3x 2 +6x+9=minus, 3, x, squared, plus, 6, x, plus, 9, equals
Answer:
-3 (x-3) (x+1)
Step-by-step explanation:
− 3 x ^2 + 6 x + 9
Factor out -3
-3( x^2 -2x-3)
The terms inside the parentheses can be factored
What 2 numbers multiplies to -3 and adds to -2
-3*1 = -3
-3+1 =-2
-3 (x-3) (x+1)
Let X and Y denote the values of two stocks at the end of a five-year period. X is uniformly distributed on the interval (0, 12). Given X = x, Y is uniformly distributed on the interval (0, x). Determine Cov(X, Y) according to this model.
Answer:
Cov (X,Y) = 6
Step-by-step explanation:
hello,
Cov(X,Y) = E(XY) - E(X)E(Y)
we must first find E(XY), E(X), and E(Y).
since X is uniformly distributed on the interval (0,12), then E(X) = 6.
next we find the joint density f(x,y) using the formula
[tex]f(x,y) = g(y|x)f_{X}(x)[/tex]
[tex]f_{X} (x) = \frac{1}{12} \ $for$\ 0<x<12[/tex] this is because f is uniformly distributed on the the interval (0,12)
also since the conditional probability density of Y given X=x, is uniformly distributed on the interval [0,x], then
[tex]g(y|x)=\frac{1}{x}[/tex] for 0≤y≤x≤12
thus
[tex]f(x,y)=\frac{1}{12x}[/tex].
hence,
[tex]E(X,Y)= \int\limits^{12}_{x=0} \int\limits^x_{y=o} xy\frac{1}{12x} \,dy dx[/tex]
[tex]E(X,Y)=\frac{!}{24} \int\limits^{12}_{x=0} x^2 \, dx = 24[/tex]
also,
[tex]E(Y) = \int\limits^{12}_{x=0} \int\limits^x_{y=0} y\frac{1}{12x} \, dydx[/tex]
[tex]E(Y)=\frac{1}{24}\int\limits^{12}_{x=0} {x} \, dx =3[/tex]
thus Cov(X,Y) = E(XY) - E(X)E(Y)
= 24 - (6)(3)
= 6
he amount of time that a customer spends waiting at an airport check-in counter is a random variable with mean 8.3 minutes and standard deviation 1.4 minutes. Suppose that a random sample of n equals 47 customers is observed. Find the probability that the average time waiting in line for these customers is
Complete question:
He amount of time that a customer spends waiting at an airport check-in counter is a random variable with mean 8.3 minutes and standard deviation 1.4 minutes. Suppose that a random sample of n equals 47 customers is observed. Find the probability that the average time waiting in line for these customers is
a) less than 8 minutes
b) between 8 and 9 minutes
c) less than 7.5 minutes
Answer:
a) 0.0708
b) 0.9291
c) 0.0000
Step-by-step explanation:
Given:
n = 47
u = 8.3 mins
s.d = 1.4 mins
a) Less than 8 minutes:
[tex]P(X<8) = P \frac{X'-u}{s.d/ \sqrt{n}} < \frac{8-8.3}{1.4/ \sqrt{47}}][/tex]
P(X' < 8) = P(Z< - 1.47)
Using the normal distribution table:
NORMSDIST(-1.47)
= 0.0708
b) between 8 and 9 minutes:
P(8< X' <9) =[tex] [\frac{8-8.3}{1.4/ \sqrt{47}}< \frac{X'-u}{s.d/ \sqrt{n}} < \frac{9-8.3}{1.4/ \sqrt{47}}][/tex]
= P(-1.47 <Z< 6.366)
= P( Z< 6.366) - P(Z< -1.47)
Using normal distribution table,
[tex] NORMSDIST(6.366)-NORMSDIST(-1.47) [/tex]
0.9999 - 0.0708
= 0.9291
c) Less than 7.5 minutes:
P(X'<7.5) = [tex] P [Z< \frac{7.5-8.3}{1.4/ \sqrt{47}}] [/tex]
P(X' < 7.5) = P(Z< -3.92)
NORMSDIST (-3.92)
= 0.0000
Kendra makes $8 per hour mowing lawns in the summer. Gas for the mower
costs $16 and will last all summer. How many hours must she mow to earn at
least $200?
Answer:
27 hours
Step-by-step explanation:
So t is going to represent time. $8t is equivalent to how much she makes for t amount of time. Being she is already down $16 for the gas, we have to take that into consideration that she must earn that back. Set up:
$8t - $16 = $200
Add like terms to get:
$8t = $216
Now solve for t by dividing both sides by $8.
t = 27 hours
4x-6 + 2x = 18
What’s the answer
Answer:
x=4
Step-by-step explanation:
4x-6 + 2x = 18
Combine like terms
6x -6 = 18
Add 6 to each side
6x-6+6 =18+6
6x = 24
Divide each side by 6
6x/6 = 24/6
x =4
6. A cone is 10 inches tall and ha s a radius of 3 inches. What is the cone’s volume? A. 31.4 cubic inches B. 94.2 cubic inches C. 282.6 cubic inches D. 847.8 cubic inches
Final answer:
To find the volume of a cone with a radius of 3 inches and a height of 10 inches, use the formula V = [tex]\frac{1}{3}[/tex] * π * r² * h. Substitute the values and calculate to find a volume of B) 94.26 cubic inches.
Explanation:
The volume of the cone can be calculated using the formula V = [tex]\frac{1}{3}[/tex] * π * r² * h.
Substitute the values for the radius (3 inches) and height (10 inches) into the formula to find the volume:
V = [tex]\frac{1}{3}[/tex] * 3.142 * 3² * 10
V = [tex]\frac{1}{3}[/tex] * 3.142 * 9 * 10
V = 94.26 cubic inches
Therefore, the cone's volume is 94.26 cubic inches.
(Based on Q1 ~ Q3) According to the Bureau of the Census, 18.1% of the U.S. population lives in the Northeast, 21.9% inn the Midwest, 36.7% in the South, and 23.3% in the West.. In a random sample of 200 recent calls to a national 800-member hotline, 39 of the calls were from the Northeast, 55 from the Midwest, 60 from the South, and 46 from the West. At the 0.05 level, can we conclude that the geographical distribution of hotline callers could be the same as the U.S. population distribution?
Answer:
We can therefore conclude that the geographical distribution of hotline callers could be the same as the U.S population distribution.
Step-by-step explanation:
The null Hypothesis: Geographical distribution of hotline callers could be the same as the U.S. population distribution
Alternative hypothesis: Geographical distribution of hotline callers could not be the same as the U.S. population distribution
The populations considered are the Midwest, South, Northeast, and west.
The number of categories, k = 4
Number of recent calls = 200
Let the number of estimated parameters that must be estimated, m = 0
The degree of freedom is given by the formula:
df = k - 1-m
df = 4 -1 - 0 = 3
Let the significance level be, α = 5% = 0.05
For α = 0.05, and df = 3,
from the chi square distribution table, the critical value = 7.815
Observed and expected frequencies of calls for each of the region:
Northeast
Observed frequency = 39
It contains 18.1% of the US Population
The probability = 0.181
Expected frequency of call = 0.181 * 200 = 36.2
Midwest
Observed frequency = 55
It contains 21.9% of the US Population
The probability = 0.219
Expected frequency of call = 0.219 * 200 =43.8
South
Observed frequency = 60
It contains 36.7% of the US Population
The probability = 0.367
Expected frequency of call = 0.367 * 200 = 73.4
West
Observed frequency = 46
It contains 23.3% of the US Population
The probability = 0.233
Expected frequency of call = 0.233 * 200 = 46
[tex]x^{2} = \sum \frac{(O_{i} - E_{i}) ^{2} }{E_{i} } , i = 1, 2,.........k[/tex]
Where [tex]O_{i} =[/tex] observed frequency
[tex]E_{i} =[/tex] Expected frequency
Calculate the test statistic value, x²
[tex]x^{2} = \frac{(39 - 36.2)^{2} }{36.2} + \frac{(55 - 43.8)^{2} }{43.8} + \frac{(60 - 73.4)^{2} }{73.4} + \frac{(46 - 46.6)^{2} }{46.6}[/tex]
[tex]x^{2} = 5.535[/tex]
Since the test statistic value, x²= 5.535 is less than the critical value = 7.815, the null hypothesis will not be rejected, i.e. it will be accepted. We can therefore conclude that the geographical distribution of hotline callers could be the same as the U.S population distribution.
A magician shuffles a standard deck of playing cards and allows an audience member to pull out a card, look at it, and replace it in the deck. Three additional people do the same. Find the probability that of the 4 cards drawn, at least 1 is a face card. (Round your answer to one decimal place.)
Answer:
0.23 or 3/13.
Step-by-step explanation:
There are 52 cards in a deck. There are four different suits, dividing the decks into 4 sets of 13. There are three face cards for each suit so 3/13. 3 divided by 13 is 0.23. Use fractions if you can because they are easier and more accurate.
To find the probability that at least one of the 4 cards drawn is a face card, calculate the probability of all cards not being face cards and subtract that from 1, resulting in approximately 64.9%.
The problem can be approached by finding the probability that none of the 4 cards drawn is a face card and then subtracting that from 1 to find the probability that at least one is a face card. There are 12 face cards in a standard deck of 52 cards, leaving 40 non-face cards. When the audience members draw and replace the cards, each draw is independent of the previous draw.
First, calculate the probability of drawing a non-face card (P(NF)):
P(NF) = number of non-face cards / total number of cards = 40/52
Since the card is replaced each time, the probability remains the same for each of the four draws. Thus, the probability that all 4 cards are non-face cards is:
P(all four are NF) = [tex]P(NF)^4 = (40/52)^4[/tex]
Then subtract this probability from 1 to get the probability of at least one face card:
P(at least one face card) = 1 - P(all four are NF)
Calculation:
P(at least one face card) = [tex]1 - (40/52)^4 = 1 - (0.7692)^4[/tex]
P(at least one face card) ≈ 1 - 0.3515 ≈ 0.6485
Therefore, the probability that at least one of the 4 cards drawn is a face card is approximately 64.9% (rounded to one decimal place).
(1,4) (6,-1) what is the y intercept of the line and how did you find it?
Answer:
Step-by-step explanation:
(1,4) (6,-1)
1-6= -5
6--1= 7 its 7 because 6 minus negative 1 would be 7
-5/7 would be your slope
---------------------------------------------------
y=mx+b
y= -5/7x+b
-1= -5/7(6)+b
-1= 6[tex]\frac{-5}{7}[/tex]+b
you take those two numbers and subtract
5 [tex]\frac{-5}{7}[/tex] is y intercept
y=[tex]\frac{-5}{7}[/tex]x+5[tex]\frac{-5}{7}[/tex]
A dead body was found within a closed room of a house where the temperature was a constant 70∘F. At the time of discovery t 1 , the core temperature of the body was determined to be 85^\circ85 ∘ F. One hour later (time t=t 1 +1,) a second measurement showed that the core temperature of the body was 80∘F. The core temperature was 98.6^\circ98.6 ∘ F at the time of death (time t=0.) Determine how many hours elapsed before the body was found.
Answer: 1.59 hours elapsed before the body was found
Step-by-step explanation: Please see the attachments below
In a sample of nequals16 lichen specimens, the researchers found the mean and standard deviation of the amount of the radioactive element, cesium-137, that was present to be 0.009 and 0.005 microcurie per milliliter, respectively. Suppose the researchers want to increase the sample size in order to estimate the mean μ to within 0.002 microcurie per milliliter of its true value, using a 95% confidence interval. Complete parts a through c.
a. What is the confidence level desired by the researchers?
b. What is the sampling error desired by the researchers?
c. Compute the sample size necessary to obtain the desired estimate.
Answer:
(a) The confidence level desired by the researchers is 95%.
(b) The sampling error is 0.002 microcurie per millilitre.
(c) The sample size necessary to obtain the desired estimate is 25.
Step-by-step explanation:
The mean and standard deviation of the amount of the radioactive element, cesium-137 present in a sample of n = 16 lichen specimen are:
[tex]\bar x=0.009\\s=0.005[/tex]
Now it is provided that the researchers want to increase the sample size in order to estimate the mean μ to within 0.002 microcurie per millilitre of its true value, using a 95% confidence interval.
The (1 - α)% confidence interval for population mean (μ) is:
[tex]CI=\bar x\pm z_{\alpha/2}\times \frac{s}{\sqrt{n}}[/tex]
(a)
The confidence level is the probability that a particular value of the parameter under study falls within a specific interval of values.
In this case the researches wants to estimate the mean using the 95% confidence interval.
Thus, the confidence level desired by the researchers is 95%.
(b)
In case of statistical analysis, during the computation of a certain statistic, to estimate the value of the parameter under study, certain error occurs which are known as the sampling error.
In case of the estimate of parameter using a confidence interval the sampling error is known as the margin of error.
In this case the margin of error is 0.002 microcurie per millilitre.
(c)
The margin of error is computed using the formula:
[tex]MOE=z_{\alpha/2}\times \frac{s}{\sqrt{n}}[/tex]
The critical value of z for 95% confidence level is:
[tex]z_{\alpha/2}=z_{0.05/2}=z_{0.025}=1.96[/tex]
*Use a z-table.
[tex]MOE=z_{\alpha/2}\times \frac{s}{\sqrt{n}}[/tex]
[tex]0.002=1.96\times \frac{0.005}{\sqrt{n}}[/tex]
[tex]n=[\frac{1.96\times 0.005}{0.002}]^{2}[/tex]
[tex]=(4.9)^{2}\\=24.01\\\approx 25[/tex]
Thus, the sample size necessary to obtain the desired estimate is 25.
A and B are complementary angles measures 32 What is the measure of b
Answer:
B = 58
Step-by-step explanation:
Complementary angles add to 90 degrees
A+B = 90
If one of the angles is 32
32+ B = 90
Subtract 32 from each side
32-32+B = 90-32
B = 58
Gabriellas school is selling tickets to a fall musical. On the dirst day of ticket sales the school sold 10 senior citizen tickets and 14 student tickets for a total of $212. Tje school took in$232 on the second day by selling 12 senior citizen tickets and 14 student tickets. What is the price each of one senior citizen tickets and one student ticket?
The smaller star has been enlarged which is a good estimated scale factor according to your evaluation of the coordinate changes
Answer:B 1.5
Step-by-step explanation:
I just did it
Answer:
B 1.5
Step-by-step explanation:
How tall is a building that casts a 74-ft shadow when the angle of elevation of the sun is 36°?
Answer:
101.85ft
Step-by-step explanation:
We can use tan here
[tex]tan\theta=\frac{opp}{adj}\\adj = \frac{opp}{tan \theta} \\adj = \frac{74}{tan(36)} = 101.85[/tex]
The height should be 101.85 ft.
Calculation of the height:Since it casts a 74-ft shadow when the angle of elevation of the sun is 36°
So, the height should be
Here we can use tan
[tex]= 74\div tan\ 36[/tex]
= 101.85 ft
Therefore, we can conclude that The height should be 101.85 ft.
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ten times a number increased by 150
Hey there!
"A number" is referred to an unknown number so we can say it is labled as
[tex]x[/tex]
"Increased" means you're going up/ adding
ten = 10
150 stays the same
"Ten times a number" =
[tex] \bf{10x}[/tex]
"Increased by 150" =
[tex] \bf{ + 150}[/tex]
Thus your answer should look like this:
[tex] \bf{10x + 150}[/tex]
Good luck on your assignment and enjoy your day!
~
[tex] \frak{loveyourselffirst }[/tex]
To solve this problem, we can use the algebraic expression 10x + 150, where 'x' represents the number.
Explanation:To solve the problem, we can translate the given phrase into an algebraic expression. Let's assume the number is represented by the variable 'x'. 'Ten times a number increased by 150' can be written as 10x + 150. This expression represents ten times the number 'x' plus 150.
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Write the word sentence as an inequality. A number h is at least −12.
Answer:
h ≥ -12
Step-by-step explanation:
at least means greater than or equal to
h ≥ -12
Answer:
h>-12
Step-by-step explanation:
multiply 3/4 x 16/19
To multiply fractions, multiply the numerators and denominators separately. For [tex]\frac{3}{4} \times \frac{16}{19}[/tex], the result is [tex]\frac{12 }{ 19}[/tex] after simplifying.
To multiply fractions, you simply multiply the numerators together and the denominators together. In this case, [tex]\frac{3}{4} \times \frac{16}{19}[/tex] would be calculated as: [tex]\frac{3 \times 16}{4 \times 19} = \frac{48 }{ 76}[/tex] This fraction can be simplified by dividing both the numerator and denominator by their greatest common factor, which in this case is 4: [tex]\frac{48 \div 4 }{ 76 \div 4 }= \frac{12 }{ 19}[/tex].
a line contains the points (-3 -2) and (7,2) determine whether the slope of this line is positive or negative
Answer:
Positive. From those two points the line would slant upwards. Going left to right it would be going up, therefore it's a positive slope
Step-by-step explanation:
The slope of the given lines with two points is positive.
How to find the slope?Slope of a line or straight object is the ratio of how much amount of rise occurs in correspondence to the increment in the run.
Thus, we get:
Slope = rise/ run
y-y₁ = m(x-x₁)
We are given that;
The points =(-3 -2) and (7,2)
Now,
For this line, let’s use (-3, -2) and (7, 2) as the two points. Plugging these values into the formula, we get:
m = (2 - (-2)) / (7 - (-3)) = 4 / 10 = 0.4
Therefore, the slope of this line is 0.4.
A positive slope means that the line goes up from left to right3. A negative slope means that the line goes down from left to right3.
Since 0.4 is a positive number,
Therefore, the slope of this line will be positive.
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Suppose x has a distribution with a mean of 50 and a standard deviation of 4. Random samples of size n = 64 are drawn. (a) Describe the x distribution and compute the mean and standard deviation of the distribution. x has distribution with mean μx = and standard deviation σx = . (b) Find the z value corresponding to x = 51. z = (c) Find P(x < 51). (Round your answer to four decimal places.) P(x < 51) =
Answer:
(a) [tex]\bar x\sim N(\mu_{\bar x}=50,\ \sigma_{\bar x}=0.5)[/tex]
(b) The z-score for the sample mean [tex]\bar x[/tex] = 51 is 2.
(c) The value of [tex]P(\bar X < 51)[/tex] is 0.9773.
Step-by-step explanation:
The random variable X has mean, μ = 50 and standard deviation, σ = 4.
A random sample of size n = 64 is selected.
(a)
According to the Central Limit Theorem if we have a population with mean μ and standard deviation σ and appropriately huge random samples (n > 30) are selected from the population with replacement, then the distribution of the sample mean will be approximately normally distributed.
Then, the mean of the distribution of sample mean is given by,
[tex]\mu_{\bar x}=\mu[/tex]
And the standard deviation of the distribution of sample mean is given by,
[tex]\sigma_{\bar x}=\frac{\sigma}{\sqrt{n}}[/tex]
The sample of X selected is, n = 64 > 30.
So, the Central limit theorem can be applied to approximate the distribution of sample mean ([tex]\bar x[/tex]).
[tex]\bar x\sim N(\mu_{\bar x}=50,\ \sigma_{\bar x}=0.5)[/tex]
(b)
The z-score for the sample mean [tex]\bar x[/tex] is given as follows:
[tex]z=\frac{\bar x-\mu_{\bar x}}{\sigma_{\bar x}}[/tex]
Compute the z-score for [tex]\bar x[/tex] = 51 as follows:
[tex]z=\frac{\bar x-\mu_{\bar x}}{\sigma_{\bar x}}[/tex]
[tex]=\frac{51-50}{0.5}\\[/tex]
[tex]=2[/tex]
Thus, the z-score for the sample mean [tex]\bar x[/tex] = 51 is 2.
(c)
Compute the value of [tex]P(\bar X < 51)[/tex] as follows:
[tex]P(\bar X < 51)=P(\frac{\bar x-\mu_{\bar x}}{\sigma_{\bar x}}<\frac{51-50}{0.5})[/tex]
[tex]=P(Z<2)\\=0.97725\\\approx 0.9773[/tex]
*Use a z-table for the probability.
Thus, the value of [tex]P(\bar X < 51)[/tex] is 0.9773.
The x distribution is normally distributed with a mean of 50 and a standard deviation of 4. The z-value corresponding to x = 51 is 0.25. The probability of x being less than 51 is approximately 0.5987.
Explanation:a) The x distribution is normally distributed with a mean of 50 and a standard deviation of 4.
The mean of the distribution is μx = 50 and the standard deviation is σx = 4.
b) To find the z-value corresponding to x = 51, we can use the formula z = (x - μ) / σ. Plugging in the values, we get z = (51 - 50) / 4 = 0.25.
c) To find P(x < 51), we can use the standard normal distribution table or a calculator to find the corresponding cumulative probability. The value is approximately 0.5987, rounded to four decimal places.
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Practice
Active
Write the ordered pair that represents yz. Then find the magnitude of yz
Y(3, 1), z{0, 4)
Answer:
[tex](y,z)=(3,5)\\\\ |(y,z)|=\sqrt{34}[/tex]
Step-by-step explanation:
Given y(3, 1), z(0, 4)
-The ordered pair is written by summing their corresponding coordanates as below:
[tex](y,z)=y(3,1)+z(0,4)\\\\=(3+0,1+4)\\\\=(3,5)[/tex]
-We then calculate the magnitude of this ordered pair as following:
[tex]|y,z|=\sqrt{y^2+z^2}\\\\=\sqrt{3^2+5^2}\\\\=\sqrt{34}\\\\\therefore |(y,z)|=\sqrt{34}[/tex]
Hence, the magnitude of the ordered pair is [tex]\sqrt{34}[/tex]
The sum of the digits of a 2-digit number is 11. If the digits are reversed, the number formed is 45 more than the original number. Find the original number
Step-by-step explanation:
Let the two-digit number be 10t+u where t is the tens digit and u the units digit.
-------------------
EQUATION:
t+u = 11
10u+t = 10t+u + 45
-------------
Rearrange the equations:
t+u = 11
9t-9u = -45
-------------
Simplify:
t+u = 11
t-u = -5
---------
Add the equations to solve for "t":
2t = 6
t = 3
--------
Substitute to solve for "u":
3+u = 11
u = 8
A survey was conducted two years ago asking college students their top motivations for using a credit card. To determine whether this distribution has changed, you randomly select 425 college students and ask each one what the top motivation is for using a credit card. Can you conclude that there has been a change in the claimed or expected distribution? Use alpha = 0.10.
Response Old Survey % New Survey Frequency
Reward 27 112
Low rate 23 96
Cash back 21 109
Discount 9 48
Others 20 60
Answer:
See explanation
Step-by-step explanation:
Solution:-
- A survey was conducted among the College students for their motivations of using credit cards two years ago. A randomly selected group of sample size n = 425 college students were selected.
- The results of the survey test taken 2 years ago and recent study are as follows:
Old Survey ( % ) New survey ( Frequency )
Reward 27 112
Low rate 23 96
Cash back 21 109
Discount 9 48
Others 20 60
- We are to test the claim for any changes in the expected distribution.
We will state the hypothesis accordingly:
Null hypothesis: The expected distribution obtained 2 years ago for the motivation behind the use of credit cards are as follows: Rewards = 27% , Low rate = 23%, Cash back = 21%, Discount = 9%, Others = 20%
Alternate Hypothesis: Any changes observed in the expected distribution of proportion of reasons for the use of credit cards by college students.
( We are to test this claim - Ha )
We apply the chi-square test for independence.
- A chi-square test for independence compares two variables in a contingency table to see if they are related. In a more general sense, it tests to see whether distributions of categorical variables differ from each other.
- We will compute the chi-square test statistics ( X^2 ) according to the following formula:
[tex]X^2 = Sum [ \frac{(O_i - E_i)^2}{Ei} ][/tex]
Where,
O_i : The observed value for ith data point
E_i : The expected value for ith data point.
- We have 5 data points.
So, Oi :Rewards = 27% , Low rate = 23%, Cash back = 21%, Discount = 9%, Others = 20% from a group of n = 425.
Ei : Rewards = 112 , Low rate = 96, Cash back = 109, Discount = 48, Others = 60.
Therefore,
[tex]X^2 = [ \frac{(112 - 425*0.27)^2}{425*0.27} + \frac{(96 - 425*0.23)^2}{425*0.23} + \frac{(109 - 425*0.21)^2}{425*0.21} + \frac{(48 - 425*0.09)^2}{425*0.09} + \frac{(60 - 425*0.20)^2}{425*0.20}]\\\\X^2 = [ 0.06590 + 0.03132 + 4.37044 + 2.48529 + 7.35294]\\\\X^2 = 14.30589[/tex]
- Then we determine the chi-square critical value ( X^2- critical ). The two parameters for evaluating the X^2- critical are:
Significance Level ( α ) = 0.10
Degree of freedom ( v ) = Data points - 1 = 5 - 1 = 4
Therefore,
X^2-critical = X^2_α,v = X^2_0.1,4
X^2-critical = 7.779
- We see that X^2 test value = 14.30589 is greater than the X^2-critical value = 7.779. The test statistics value lies in the rejection region. Hence, the Null hypothesis is rejected.
Conclusion:-
This provides us enough evidence to conclude that there as been a change in the claimed/expected distribution of the motivations of college students to use credit cards.
Final answer:
To test for changes in credit card usage motivations among college students, calculate the expected frequencies from the old survey percentages, apply the chi-square goodness-of-fit test, and compare the statistic to the chi-square critical value at alpha = 0.10.
Explanation:
Understanding the Hypothesis Test for Changed Distribution
To determine whether there has been a shift in the distribution of college students' motivations for using credit cards since the previous survey, we conduct a hypothesis test for goodness of fit. The test will compare the observed frequencies from the new survey with the expected frequencies based on the old survey percentages.
First, calculate the expected frequency for each category using the formula: Expected Frequency = (Old Survey Percentage / 100) × Total Number of Students. Then, employ the chi-square goodness-of-fit test to analyze the data:
Reward: Expected = 0.27 × 425 = 114.75
Low rate: Expected = 0.23 × 425 = 97.75
Cash back: Expected = 0.21 × 425 = 89.25
Discount: Expected = 0.09 × 425 = 38.25
Others: Expected = 0.20 × 425 = 85.00
With the expected frequencies calculated, the chi-square statistic will be computed:
χ² = Σ((Observed - Expected) ² / Expected)
This statistic will be compared to a critical value from the chi-square distribution table with (n - 1) degrees of freedom, where n is the number of categories, at alpha = 0.10 to determine whether to reject the null hypothesis (no change in distribution).
Before starting their graduate studies, a student wants to rent an apartment near the university. She wants to learn how the distance to the school affects the rent. Statistical software was used to conduct a simple linear regression about the relationship between the rent (in USD) of an apartment and its distance to the university (in miles). The following equation for the regression line was given: RENT = 1200.4326 - 256.2567 DISTANCE Say someone lives 0.43 miles from campus and pays $1,050 a month in rent. What is the resulting residual value? Give your answer to two decimal places. For help on how to input a numeric answer, please see "Instructions for inputting a numeric response."
Answer:
The resulting residual value is e=-40.24.
Step-by-step explanation:
The residual value e for a regression model is defined as the difference between the real value y and the predicted value yp:
[tex]e=y-y_p[/tex]
The predicted value for DISTANCE=0.43 miles is:
[tex]RENT = 1200.4326 - 256.2567\cdot DISTANCE\\\\RENT(0.43) = 1200.4326 - 256.2567\cdot 0.43\\\\RENT(0.43) = 1200.4326 - 110.1904=1090.2422\\\\[/tex]
Then, if the real value is $1,050, the residual value is calculated as:
[tex]e=y-y_p\\\\e=1050-1090.2422=-40.2422[/tex]
Suppose the allowable increase and decrease for an objective coefficient of a decision variable that has a current value of $50 are $25 (increase) and $10 (decrease). If the coefficient were to change from $50 to $60, the optimal value of the objective function would not change.
1.True
2.False
Determine whether the samples are independent or dependent. To test the effectiveness of a drug comma cholesterol levels are measured in 200 men and 200 women after the treatment. Choose the correct answer below. A. The samples are independent because there is a natural pairing between the two samples. B. The samples are dependent because there is a natural pairing between the two samples. C. The samples are independent because there is not a natural pairing between the two samples.
Answer:
C
Step-by-step explanation:
The samples are independent because there is not a natural pairing between the two samples.
Since Independent samples are samples that are selected randomly so that its observations do not depend on the values other observations also data set in which each data point in one sample is not paired to a data point in the second sample
A study was done on the timeliness of flights (on-time vs. delayed) of two major airlines: StatsAir and AirMedian. Data were collected over a period of time from five major cities and it was found that StatsAir does better overall (i.e., has a smaller percentage of delayed flights). However, in each of the five cities separately, AirMedian does better.
Which of the following is correct?
(a) This situation is mathematically impossible.
(b) This is an example of Simpson's Paradox.
(c) "City" is a lurking variable in this example.
(d) This is an example of a negative association between variables.
(e) Both (b) and (c) are correct.
Answer:
The answer is Option E; both B and C are correct
Step-by-step explanation:
Both (b) and (c) are correct. Simpson's paradox is a paradox in which a trend that appears in different groups of data disappears when these groups are combined, and the reverse trend appears for the aggregate data. This result is often encountered in social-science and medical-science statistics, and is particularly confounding when frequency data are unduly given causal interpretations. Simpson's Paradox disappears when causal relations are brought into consideration.
Now, this question is an example of Simpsons paradox because the groups of collected data over a period of time from five major cities showed a trend that StatsAir does better overall, but this trend is reversed when the groups are studied separately to show that air median does better.
So, option B is correct.
Also, City is a variable that influences both the dependent variable and independent variable, causing a spurious association. That is it is the cause of why the 2 results are biased. Thus, city is a lurking variable.
So, option C is also correct
The number of undergraduates at Johns Hopkins University is approximately 2000, while the number at Ohio State University is approximately 40,000. A simple random sample of 50 undergraduates at Johns Hopkins University will be obtained to estimate the proportion of all Johns Hopkins students who feel that drinking is a problem among college students. A simple random sample of 50 undergraduates at Ohio State University will be obtained to estimate the proportion of all Ohio State students who feel that drinking is a problem among college students. Answer Questions 4-5 below.
The remaining part of Question:
4) what can we conclude about sampling variability in the sample proportion calculated in the sample at John Hopkins as compared to that calculated in the sample at Ohio State.
5) The number of undergraduates at Johns Hopkins is approximately 2000 while the number at Ohio State is approximately 40000, suppose instead that at both schools, a simple random sample of about 3% of the undergraduates Will be taken.
Answer:
4) The sample proportion from Johns Hopkins will have about the same sampling variability as that from Ohio State
5) The sample proportion from John Hopkins will have more sampling variability than that from Ohio State
Step-by-step explanation:
Note: The sampling variability in the sample proportion decreases with increase in the sample size.
4) since the sample size at both Johns Hopkins and Ohio State is the same (i.e. n = 50), the sample variability of the sample proportion will be the same for both cases.
5) 3% of the population are selected for the observation in both cases.
At Johns Hopkins, sample size, n = 3% * 2000
n = 60
At Ohio State, sample size, n = 3% * 40000
n = 1200
Since sampling variability in the sample proportion decreases with increase in the sample size, the sampling variability in sample proportion will be higher at Johns Hopkins than at Ohio State.
A researcher wants to study exercise as a way of reducing anger expression. He plans to throw water balloons at participants, measure their anger using behavioral cues (e.g., number of swear words, redness of face, etc.), make them do 20 pushups, then measure their anger again. He wants to see if there are differences before and after 20 pushups. Which t-test should he use? a. Single sample b. Paired samples c. Independent samples
Answer:
Option B: Paired sample t-test, since there is a "before 20 push ups" and "after 20 push up " score for each participant.
Step-by-step explanation:
In this question, we have a case where each participant undergoes different exercises to see differences before and after 20 push ups.
Now, it's obvious that the same condition applies to all participants i.e. differences before and after 20 push ups.
Thus, this will be a case of paired sample t-test or dependent t test because conditions for all participants in both tests are dependent or same.
So, the only option that corresponds with my explanation to use paired sample is option B