The quotient of a number increased by 13 and -7 is -4

Answers

Answer 1
Final answer:

The number in question is found by setting up the equation (x + 13) / -7 = -4, and solving for 'x'. Following order of operations and sign rules, we determine that the number is 15.

Explanation:

The question asks us to find a number when given that the quotient of that number increased by 13 and -7 is -4. To solve this, we set up an equation and follow the multiplication and division rules for signs and the order of operations.

Let the unknown number be 'x'. According to the problem, (x + 13) / -7 = -4. Multiplying both sides by -7 to eliminate the denominator, we get x + 13 = (-7)(-4). Applying the rule that the product of two negative numbers is positive, we simplify the right side to get x + 13 = 28. Now, we subtract 13 from both sides to isolate 'x': x = 28 - 13, which gives us x = 15.

The number in question is therefore 15.


Related Questions

draw a rectangle that is 28 units by 12 units

Answers

Answer:

Attached

Step-by-step explanation:

On a cartessian plane, we take four points as shown. Point A has coordinates as (4, 0) while point B is (32, 0). Since the y cordinates are zero, don't change, only x change. Change in x coordinates is 32-4=28 units.

Point C is (32, 12) where x has not changed when compared to point B but y changes by 12-0=12 units

Therefore, the diagram is triangle whose length is 28 units while width is 12 units.

Rebekah wants to read a certain number of pages each day during summer vacation.
Today, she read 204 pages, which is 136% of her goal.
How many pages does Rebekah want to read each day?
A. 75 pages
B. 130 pages
C. 150 pages
D. 560 pages

Answers

Answer:

C. 150 pages

Step-by-step explanation:

204 divided by 136 = 1.5

1.5 * 100 = 150

Hope it helps! :)

The answer is C

204 divided by 136 = 1.5

1.5 • 100 = 150

Find the area of the triangle 10cm 15 cm

Answers

Answer:

75 cm (if b=10 and h=15)

Step-by-step explanation:

The formula to calculate the area of a triangle is bh1/2. So you must do (10)(15)1/2, 10 multiplied by 15 equals 150. And 150 multiplied by 1/2 equals 75. Hope this helped!

A very large study showed that aspirin reduced the rate of first heart attacks by 44%. A pharmaceutical company thinks they have a drug that will be more effective than aspirin, and plans to do a randomized clinical trial to test the new drug. a) What is the null hypothesis the company will use? b) What is their alternative hypothesis?c) Is this question dealing with 1 mean or 1 proportion

Answers

Answer:

a) Null hypothesis: [tex]p \leq 0.44[/tex]

b) Alternative hypothesis: [tex]p > 0.44[/tex]

c) For this case our parameter of interest is a proportion "reduced rate of first heart attacks for a new drug". for this reason the answer would be 1 proportion and we can conduct the hypothesis with a 1 z proportion test  

Step-by-step explanation:

For this case the pharmaceutical company thinks they have a drug that will be more effective than aspirin and on this case that means a better rate in order to reduce the heart attacks (that represent the alternative hypothesis since that;s what they want to proof), and the complement would be the null hypothesis.

Part a

Null hypothesis: [tex]p \leq 0.44[/tex]

Part b

Alternative hypothesis: [tex]p > 0.44[/tex]

Part c

For this case our parameter of interest is a proportion "reduced rate of first heart attacks for a new drug". for this reason the answer would be 1 proportion and we can conduct the hypothesis with a 1 z proportion test  

When faced with a problem or choice, humans can use two different strategies: "cognitive reflectivity," which results in slower responses and few mistakes, or "cognitive impulsivity," which results in quicker responses but also more mistakes. Depending on the individual, these two strategies are used differently.
A pilot experiment was conducted on 22 right-handed individuals who were administered a cognitive reflectivity-impulsivity questionnaire, while recording voxel-based morphometry (regional gray matter density) in the ventral medial prefrontal cortex.1. Based on the experimental design and the kind of data collected, which statistical test(s) should be used to determine whether there is an association between the cognitive strategy, cognitive reflectivity and the gray matter density of the ventral medial prefrontal cortex?
Select all that apply!O t-test of zero linear correlationO One-way ANOVAO z-testO correlation coefficient (r)O two sample t-test

Answers

Based on the experimental design and the data collected the statistical test that should be used is the correlation coefficient.

What are statistical tests?

The statistical tests are tests that are used by researchers to determine the progress of a set process and make a quantitative decision during analysis of test results.

Example of statistical tests include the following:

t-test of zero linear correlation,

One-way ANOVA,

z-test,

correlation coefficient, and

two sample t-test.

The correlation coefficient which is a type of statistical test is used to assess the strength and direction of the linear relationships between pairs of variables.

Therefore, the relationship between cognitive reflectivity and cognitive impulsivity in human data can be statistically analysed using correlation coefficient.

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According to a report in USAToday, more and more parents are helping their young adult children get homes. Suppose eight persons in a random sample of 40 young adults who recently purchased a home in Kentucky received help from their parents. You have been asked to construct a 95% confidence interval for the population proportion of all young adults in Kentucky who received help from their parents. What is the margin of error for a 95% confidence interval for the population proportion?

Answers

Answer:

a)  95% confidence interval for the population proportion of all young adults in Kentucky who received help from their parents.

( 0.0761 , 0.3239)

b) Margin of error  =  0.1264.

Step-by-step explanation:

Explanation:-

Given '8' persons in a random sample of 40 young adults who recently purchased a home in Kentucky received help from their parents.

sample proportion of success [tex]'p' = \frac{8}{40} = 0.2[/tex]

q = 1=p

q = 1-0.2 = 0.8

a)

95% confidence interval for the population proportion of all young adults in Kentucky who received help from their parents.

[tex](p-1.96\sqrt{\frac{pq}{n} } , p+1.96\sqrt{\frac{pq}{n} } )[/tex]

[tex](0.2-1.96\sqrt{\frac{0.2X0.8}{40} } , 0.2+1.96\sqrt{\frac{0.2X0.8}{40} } )[/tex]

(0.2 - 0.1239,0.2+0.1239)

( 0.0761 , 0.3239)

b) the margin of error for a 95% confidence interval for the population proportion.

For the 95% confidence interval ∝= 0.05 and zₐ = 1.96≅2.

[tex]Margin of error = \frac{2\sqrt{pq} }{\sqrt{n} }[/tex]

[tex]Margin of error = \frac{2\sqrt{0.2X0.8} }{\sqrt{40} }[/tex]

Margin of error for a 95% confidence interval for the population proportion.

Margin of error  =  0.1264.

jerome filled bags with trail mix. the weights of the bags are

Answers

How ever much they weigh on the scale

A total of 1 232 students have taken a course in Spanish, 879 have taken a course in French, and 114 have taken a course in Russian. Further, 103 have taken courses in both Spanish and French, 23 have taken courses in both Spanish and Russian, and 14 have taken courses in both French and Russian. If 2 092 students have taken at least one of Spanish, French, and Russian, how many students have taken a course in all three languages

Answers

Answer:

[tex]n(S\cap F \cap R)=7[/tex]

Step-by-step explanation:

The Universal Set, n(U)=2092

[tex]n(S)=1232\\n(F)=879\\n(R)=114[/tex]

[tex]n(S\cap R)=23\\n(S\cap F)=103\\n(F\cap R)=14[/tex]

Let the number who take all three subjects, [tex]n(S\cap F \cap R)=x[/tex]

Note that in the Venn Diagram, we have subtracted [tex]n(S\cap F \cap R)=x[/tex] from each of the intersection of two sets.

The next step is to determine the number of students who study only each of the courses.

[tex]n(S\:only)=1232-[103-x+x+23-x]=1106+x\\n(F\: only)=879-[103-x+x+14-x]=762+x\\n(R\:only)=114-[23-x+x+14-x]=77+x[/tex]

These values are substituted in the second Venn diagram

Adding up all the values

2092=[1106+x]+[103-x]+x+[23-x]+[762+x]+[14-x]+[77+x]

2092=2085+x

x=2092-2085

x=7

The number of students who have taken courses in all three subjects, [tex]n(S\cap F \cap R)=7[/tex]

Using the principle of Inclusion-Exclusion, we find that 7 students have taken courses in all three languages: Spanish, French, and Russian.

Finding the Number of Students Taking All Three Language Courses

We can solve this problem using the principle of Inclusion-Exclusion. Let:
S = number of students taking Spanish
F = number of students taking French
R = number of students taking Russian
SF = number of students taking both Spanish and French
SR = number of students taking both Spanish and Russian
FR = number of students taking both French and Russian
SFR = number of students taking all three languages.

From the given data:

S = 1232F = 879R = 114SF = 103SR = 23FR = 14Total students taking at least one language = 2092

The principle of Inclusion-Exclusion states:

Total = S + F + R - SF - SR - FR + SFR
2092 = 1232 + 879 + 114 - 103 - 23 - 14 + SFR

Solving for SFR:

2092 = 2085 + SFR

Thus, SFR = 2092 - 2085 = 7

Therefore, 7 students have taken courses in all three languages: Spanish, French, and Russian.

what is the slope intercept form of 2x-3y=9

Answers

Answer:

-3y=-2x+9

Step-by-step explanation:

flip the value

when flipping a value remember to invert its sign

Simplify the following equation as best as you can.
-6.4m + 4(0.5m - 0.8)

Answers

Answer:

-4.4m-3.2

Step-by-step explanation:

-6.4m+4(0.5m-0.8)

-6.4m+4*0.5+4*0.8

-6.4m+2m-3.2

-4.4m-3.2

Answer:

-4.4m-3.2

Step-by-step explanation:

multiply everything in the parentheses by 4 and then add.

ASK YOUR TEACHER An experiment to compare the tension bond strength of polymer latex modified mortar (Portland cement mortar to which polymer latex emulsions have been added during mixing) to that of unmodified mortar resulted in x = 18.11 kgf/cm2 for the modified mortar (m = 42) and y = 16.83 kgf/cm2 for the unmodified mortar (n = 30). Let μ1 and μ2 be the true average tension bond strengths for the modified and unmodified mortars, respectively. Assume that the bond strength distributions are both normal. (a) Assuming that σ1 = 1.6 and σ2 = 1.3, test H0: μ1 − μ2 = 0 versus Ha: μ1 − μ2 > 0 at level 0.01. Calculate the test statistic and determine the P-value. (Round your test statistic to two decimal places and your P-value to four decimal places.)

Answers

Answer:

Test statistics = 3.74

P-value = 0.0001

Step-by-step explanation:

We are given that an experiment to compare the tension bond strength of polymer latex modified mortar to that of unmodified mortar resulted in x = 18.11 kg f/[tex]cm^{2}[/tex] for the modified mortar (m = 42) and y = 16.83 kg f/[tex]cm^{2}[/tex] for the unmodified mortar (n = 30).

Assume that the bond strength distributions are both normal and assuming that σ1 = 1.6 and σ2 = 1.3.

Let [tex]\mu_1[/tex] = true average tension bond strengths for the modified mortars

      [tex]\mu_2[/tex] = true average tension bond strengths for the unmodified mortars

So, Null Hypothesis, [tex]H_0[/tex] : [tex]\mu_1-\mu_2=0[/tex]  or  [tex]\mu_1=\mu_2[/tex]    {means that true average tension bond strengths for the modified and unmodified mortars are same}

Alternate Hypothesis, [tex]H_a[/tex] : [tex]\mu_1-\mu_2>0[/tex]  or  [tex]\mu_1>\mu_2[/tex]    {means that the true average tension bond strengths for the modified mortars is greater than that for unmodified mortars}

The test statistics that will be used here is Two-sample z test statistics as we know about population standard deviations;

               T.S.  =  [tex]\frac{(x-y)-(\mu_1-\mu_2)}{\sqrt{\frac{\sigma_1^{2} }{m}+\frac{\sigma_2^{2} }{n} } }[/tex]  ~ N(0,1)

where, x = sample mean tension bond strengths for the modified mortars = 18.11 kg f/[tex]cm^{2}[/tex]

         y = sample mean tension bond strengths for the unmodified mortars = 16.83 kg f/[tex]cm^{2}[/tex]

         [tex]\sigma_1[/tex] = population standard deviation for modified mortars = 1.6

         [tex]\sigma_2[/tex] = population standard deviation for unmodified mortars = 1.3

         m = sample of modified mortars = 42

         n = sample of unmodified mortars = 30

So, test statistics  =  [tex]\frac{(18.11-16.83)-(0)}{\sqrt{\frac{1.6^{2} }{42}+\frac{1.3^{2} }{30} } }[/tex]

                               =  3.74

Now, P-value is given by the following formula;

         P-value = P(Z > 3.74) = 1 - P(Z [tex]\leq[/tex] 3.74)  

                                            = 1 - 0.9999 = 0.0001

Here, the above probability is calculated by looking at the value of x = 3.74 in the z table which gives an area of 0.9999.

Final answer:

To test the hypothesis H0: μ1 − μ2 = 0 versus Ha: μ1 − μ2 > 0 at level 0.01, calculate the test statistic and the P-value. The test statistic is Z = (x - y) / √((σ1² / m) + (σ2² / n)). Substituting the values gives Z = 1.278. The P-value is approximately 0.1019.

Explanation:

To test the hypothesis H0: μ1 − μ2 = 0 versus Ha: μ1 − μ2 > 0 at level 0.01, we calculate the test statistic and the P-value. The test statistic is given by:

Z = (x - y) / √((σ1² / m) + (σ2² / n))

where x = 18.11, y = 16.83, σ1 = 1.6, σ2 = 1.3, m = 42, and n = 30.

Substituting the values, we get Z = (18.11 - 16.83) / √((1.6² / 42) + (1.3² / 30)).

Calculating Z gives Z = 1.278. To determine the P-value, we find the area to the right of Z in the standard normal distribution. The P-value is the probability that Z > 1.278. Consulting a Z-table or using a calculator, we find the P-value to be approximately 0.1019.

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The endpoints of the longest chord on a circle are (4, 5.5) and (4, 10.5).
The center of the circle is at the point , and its radius is units. The equation of this circle in standard form is .

Answers

Answer:

Read the explanation for the answers

Step-by-step explanation:

To find the midpoint, you simply need to find the average of the two endpoints. The average of 10.5 and 5.5 is 8, and the average of 4 and 4 is 4. Therefore, the center of the circle is at (4,8). The radius is the distance from the center to either of these points, or 8-5.5=2.5 units. And finally, the formula for the circle in standard form is [tex](y-8)^2+(x-4)^2=6.25[/tex]. Hope this helps!

Which point has coordinates of (2, 0)?

Answers

Answer:

J

Step-by-step explanation:

A new manager of a small convenience store randomly samples 20 purchases from yesterday’s sales. The mean was $45.26 and the standard deviation was $20.67. We wish to test for evidence that the overall mean purchase amount is at least $40? What is the value of the t-statistic for this test (three decimal places)?

Answers

Answer:

The value of the t-statistic for this test is 1.138.

Step-by-step explanation:

We are given that a new manager of a small convenience store randomly samples 20 purchases from yesterday’s sales. The mean was $45.26 and the standard deviation was $20.67.

We wish to test for evidence that the overall mean purchase amount is at least $40

Let [tex]\mu[/tex] = overall mean purchase amount

SO, Null Hypothesis, [tex]H_0[/tex] : [tex]\mu[/tex] [tex]\geq[/tex] $40   {means that the overall mean purchase amount is at least $40}

Alternate Hypothesis, [tex]H_A[/tex] : [tex]\mu[/tex] < $40   {means that the overall mean purchase amount is less than $40}

The test statistics that will be used here is One-sample t test statistics because we don't know about the population standard deviation;

                           T.S.  = [tex]\frac{\bar X -\mu}{{\frac{s}{\sqrt{n} } } }[/tex]  ~ [tex]t_n_-_1[/tex]

where,  [tex]\bar X[/tex] = sample mean sale = $45.26

              s = sample standard deviation = $20.67

              n = sample of purchases = 20

So, test statistics  =  [tex]\frac{45.26-40}{{\frac{20.67}{\sqrt{20} } } }[/tex]  ~ [tex]t_1_9[/tex]

                               =  1.138

Hence, the value of the t-statistic for this test is 1.138.

Consider the reduction of the rectangle


Rounded to the nearest tenth, what is the value of x?.

A.0.1 feet

B.0.6 feet

C.1.6 feet

D.2.0 feet

Answers

The question is incomplete. The complete question is as follows.

Consider the reduction of the rectangle. A large rectangle has a length of 16.8 feet and width of 2.3 feet. A smaller rectangle has a length of 4.5 feet and width of x feet. Not drawn to scale (The drawing is in the attachment). Rounded to the nearest tenth.  

What is the value of x?

A. 0.1 feet

B. 0.6 feet

C. 1.6 feet

D. 2.0 feet

Answer: B. 0.6 feet

Step-by-step explanation: Two quantity are proportional if the ratio of them is constant. From the drawing and the question, we have that the two rectangles are proportional between them.

[tex]\frac{x}{2.3} = \frac{4.5}{16.8}[/tex]

[tex]x = \frac{4.5*2.3}{16.8}[/tex]

x = [tex]\frac{10.35}{16.8}[/tex]

x = 0.6

The width of the smaller rectangle is 0.6 feet.

Answer: 0.6 ft.

Step-by-step explanation: 16.8/4.5= 3.733333333 repeating. The scale factor is 3.73333333333 repeating. 2.3/3.733333333333 Repeating equals .61607142857. We can shorten it to .61, and it says rounded to the nearest tenth, so .61 rounded is 0.6.

Which polynomials are prime? Check all of the boxes that apply.
x² +9
x²_9
x2 + 3x + 9
-2x² +8

Answers

Answer: x^2+9 and x^2+3x+9

Step-by-step explanation:

Final answer:

A polynomial is prime if it cannot be factored into polynomials of lower degree. In this case, x² +9 and x² + 3x + 9 are prime polynomials while x² -9 and -2x² +8 are not.

Explanation:

In mathematics, a polynomial is said to be prime if it cannot be factored into polynomials of lower degree, at least one of which must be non-constant. To determine if a polynomial is prime, we try to factor it. In our case:

x² +9 is a prime polynomial because it is a sum of squares and cannot be factored into real polynomials of lower degree. x² -9 is not a prime polynomial because it can be factored into (x-3)(x+3). x² + 3x + 9 is a prime polynomial because it cannot be factored into real polynomials of lower degree. -2x² +8 is not a prime polynomial as it can be factored into -2(x²-4).

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You would like to determine if there is a higher incidence of smoking among women than among men in a neighborhood. Let women and men be represented by populations 1 and 2, respectively. The relevant hypotheses are constructed as ____________.

H0: Mue1-Mue2 less than or equal 0.

Ha: Mue1-Mue2>0

H0: Mue1-Mue greater or equal 0.

Ha: Mue1-Mue<0

H0: P1-P2 less than or equal 0

Ha: P1-P2>0

H0: P1-P2 greater than or 0

Ha: P1-P2<0

Answers

Answer:

H₀: p₁ - p₂ < 0.

Hₐ: p₁ - p₂ > 0.

Step-by-step explanation:

In this case, we need to determine if there is a higher incidence of smoking among women than among men in a neighborhood.

An experiment can be performed involving collecting two samples of men and women and computing the proportion of men and women smokers in the neighborhood. Then these two sample proportions can be used to determine which proportion is higher.

We are computing proportions of men and women smokers instead of the mean number of men and women smokers because the we need to determine the  incidence of smoking among men and women, i.e. the occurrence or frequency or rate of men and women smokers.

So, a two proportion test can be applied to determine whether the proportion of women smokers is higher than men.

The population proportion of women in the neighborhood is represented by p and the  population proportion of men in the neighborhood is represented by p.

The hypothesis can be defined as:

H₀: The proportion of women smokers is not higher than men, i.e. p₁ - p₂ < 0.

Hₐ: The proportion of women smokers is higher than men, i.e. p₁ - p₂ > 0.

Final answer:

The null hypothesis (H0) should be P1 - P2 ≥ 0, indicating no higher incidence of smoking among women, and the alternative hypothesis (Ha) should be P1 - P2 < 0, suggesting a higher incidence of smoking among women.

Explanation:

When conducting a hypothesis test to determine if there's a higher incidence of smoking among women than among men in a neighborhood, you would use two hypotheses: the null hypothesis (H0) and the alternative hypothesis (Ha). Since we are looking to find if the incidence is higher in women, the null hypothesis should reflect there is no difference or that the incidence in women is less than or equal to the incidence in men. Therefore, the correct setup using population proportions (P1 for men and P2 for women) would be:

H0: P1 - P2 ≥ 0 (there is no higher incidence of smoking among women compared to men)Ha: P1 - P2 < 0 (there is a higher incidence of smoking among women compared to men)

The null hypothesis statement is that the proportion of women who smoke is less than or equal to the proportion of men who smoke. The alternative hypothesis is what you intend to prove, which is that more women smoke than men in the neighborhood, hence P1 - P2 < 0. This would be considered a left-tailed test.

25 points!!!!!!!!!!!!!!!!!!!!!!!!!

3.5 in to fraction with 5 repeating
plz help ill rate 5 star






Answers

Answer:

32/9 or 3 5/9

Step-by-step explanation:

3.5555

3 5/9

(3×9 + 5)/9

32/9

Answer:

x = 32/9

Step-by-step explanation:

Let x = 3.55555555repeating

Multiply by 10

10x = 35.555555 repeating

Subtract the first equation

10x = 35.555555 repeating

-x = 3.55555555repeating

-------------------------------------

9x = 32

Divide each side by 9

9x/9 = 32/9

x = 32/9

Use Demoivres Theorem to find (1 + i) 20.
a. 1024i
b. -1024
C.-1024
D.1024

Answers

Answer:

-1024

Step-by-step explanation:

Moivre's theorem allows to easily obtain trigonometric formulas that express the sine and cosine of a multiple angle as a function of the sine and cosine of a simple angle.

De Moivre's theorem can be applied to any complex number [tex]z[/tex]

Where:

[tex]z\in Z[/tex]

Let:

[tex](1+i)=z\\n=20[/tex]

According to Demoivres Theorem, If:

[tex]z=||z||(cos(\theta)+isin(\theta))[/tex]

Then:

[tex]z^n=||z||^n(cos(n\theta)+isin(n\theta))[/tex]

For a complex number [tex]z[/tex]:

[tex]z=a+bi[/tex]

Its magnitude and angle are given by:

[tex]||z||=\sqrt{a^2+b^2} \\\\\theta=arctan(\frac{b}{a} )[/tex]

So:

[tex]||z||=\sqrt{1^2+1^2} =\sqrt{2}[/tex]

[tex]\theta=arctan(\frac{1}{1} )=45^{\circ}[/tex]

Therefore, using De Moivre's theorem:

[tex]z^n=(\sqrt{2} )^{20}(cos(20*45)+isin(20*45))\\\\z^n=(\sqrt{2} )^{20}(cos(900)+isin(900))\\\\z^n=1024(-1+i(0))\\\\z^n=1024(-1)\\\\z^n=(1+i)^{20}=-1024[/tex]

C on e2020

i did it *dab*

Simplify the product using the distributive property. (5h - 5)(5h - 6)

Answers

multiplying them together gives 25h^2-55h+30

Six people, named Anna, Bob, Chandra, Darlene, Ed, and Frank, will be interviewed for a job. The interviewer will choose two at random to interview on the first day. What is the probability that Darlene is interviewed first and Bob is interviewed second? Express your answer as a fraction or a decimal, rounded to four decimal places.

Answers

Your answer is 1/30, or 0.0333

The interviewer has a 1/6 chance of choosing Darlene first because all of the people have an equal chance and there are 6 people.
The interviewer then has a 1/5 chance of choosing Bob second, because Darlene has already been chosen so there are now only 5 people to choose from.

Therefore we do 1/6 × 1/5 = 1/30 = 0.0333

I hope this helps!

Answer:

there is a 1/18th percent chance Darlene and bob will go in that order

Step-by-step explanation:

What is the product of (3y+4)2

Answers

Answer:

6y+8

Step-by-step explanation:

You should apply distributive property of the product, and multiply 2 by 3y and then add to that result the product of 2 times 4: [tex](3y+4)\times2= 2\times3y+2\times4=6y+8[/tex].

A survey reported that 5% of Americans are afraid of being alone in a house at night. If a random sample of 20 Americans is selected, what is the probability that exactly 3 people in the sample are afraid of being alone at night.

Answers

Final answer:

The probability that exactly 3 people out of a sample of 20 Americans are afraid of being alone in a house at night, given that 5% of Americans have this fear, is approximately 13.98%.

Explanation:

The question asks for the probability that exactly 3 people in a sample of 20 Americans are afraid of being alone in a house at night, given that 5% of Americans have this fear. This can be solved using the binomial probability formula, which is P(X = k) = C(n, k) * p^k * (1-p)^(n-k), where n is the number of trials, k is the number of successful trials, p is the probability of success on an individual trial, and C(n, k) is the number of combinations of n items taken k at a time.

Plugging in the values, we get P(X = 3) = C(20, 3) * 0.05³* 0.95¹⁷ First, calculate C(20, 3) = 20! / (3!(20-3)!) = 1140. Then calculate the probability: P(X = 3) = 1140 * 0.05³* 0.95¹⁷.

Doing the math, P(X = 3) ≈ 0.1398, or approximately 13.98%.

Final answer:

The probability that exactly 3 out of 20 Americans are afraid of being alone at night is found by using the binomial probability formula, which incorporates the number of people in the sample, the number who are afraid, and the overall chance of fear of being alone at night.

Explanation:

To find the probability that exactly 3 people out of a random sample of 20 Americans are afraid of being alone at night when it is known that 5% of Americans have this fear, we can use the binomial probability formula:

P(X = k) = C(n, k) * p^k * (1-p)^(n-k)

Where:

n is the number of trials (in this case, 20)

k is the number of successes (in this case, 3)

p is the probability of success on an individual trial (5% or 0.05)

C(n, k) is the number of combinations of n things taken k at a time

Let's calculate:

Compute C(20, 3): This is 20! / (3! * (20-3)!).

Calculate p^k, which is 0.05^3.

Calculate (1-p)^(n-k), which is (1-0.05)^(20-3).

Multiply these together to get the probability.

After performing the calculations, we determine the probability of exactly 3 out of 20 Americans being afraid of being alone at night.

A cable runs along the wall from C to P at a cost of ​$4 per​ meter, and straight from P to M at a cost of ​$5 per meter. If M is 9 meters from the nearest point A on the wall where P​ lies, and A is 33 meters from​ C, find the distance from C to P such that the cost of installing the cable is minimized and find this cost.

Answers

Answer:

The minimum cost of installing the cable is $156.

Step-by-step explanation:

We have an optimization problem.

We have to minimize the cost of the cable.

We will use the variable x to express the the length of cable CP and PM, accordingly to the attache picture.

The length of the cable that goes from C to P (let's call it CP) is x.

[tex]\bar{CP}=x[/tex]

Then, the length of the cable that goes from P to M (PM) can be calcualted usign the Pithagorean theorem:

[tex]\bar{PM}=\sqrt{(33-x)^2+9^2}[/tex]

The cost function Y is:

[tex]Y=4*\bar{CP}+5*\bar{PM}=4x+5\sqrt{(33-x)^2+9^2}[/tex]

To optimize this cost funtion we have to derive and equal to 0:

[tex]\dfrac{dY}{dx}=0\\\\\\\dfrac{dY}{dx}=4+5(\dfrac{1}{2})((33-x)^2+9^2)^{-1/2} *(-2)(33-x)\\\\\\\dfrac{dY}{dx}=4+5\dfrac{x-33}{\sqrt{(33-x)^2+81}}=0\\\\\\\dfrac{x-33}{\sqrt{(33-x)^2+81}}=-\dfrac{4}{5}\\\\\\(x-33)=-\dfrac{4}{5}\sqrt{(33-x)^2+81}\\\\\\(x-33)^2=(-\dfrac{4}{5})^2[(x-33)^2+81]\\\\\\(x-33)^2=\dfrac{16}{25}(x-33)^2+\dfrac{1296}{25}\\\\\\\dfrac{25-16}{25} (x-33)^2=\dfrac{1296}{25}\\\\\\9(x-33)^2=1296\\\\\\x-33=\sqrt{\dfrac{1296}{9}}=\sqrt{144}=\pm12\\\\\\x=33\pm12\\\\\\x_1=33-12=21\\\\x_2=33+12=45[/tex]

The valid solution is x=21, as x can not phisically larger than 33.

The cost then becomes:

[tex]Y=4*\bar{CP}+5*\bar{PM}=4x+5\sqrt{(33-x)^2+9^2}\\\\\\Y=4*21+5\sqrt{(33-21)^2+81}\\\\Y=81+5\sqrt{144+81}\\\\Y=81+5\sqrt{225}\\\\Y=81+5*15\\\\Y=81+75\\\\Y=156[/tex]

Final answer:

This optimization problem in calculus can be solved by setting up a cost function for the total cable installation, taking its derivative, setting it equal to 0 to find the critical points, which will give you the distance from C to P that minimizes cost, check this point for being minimal and calculating the minimal cost by substituting the found distance into the originally defined cost function.

Explanation:

The problem can be solved using the calculus principle of optimization. The situation described in your question makes a right triangle AMP. In this triangle, the vertical side (AP) measures 9 meters, and the hypotenuse (PM) represents cable installation that costs $5 per meter. The distance PC along the wall is $4 per meter. The cost of total cable installation from C -> P -> M is given as follows:

Cost = 4 * length CP + 5 * length PM

By the Pythagorean theorem, we know that [tex]PM = \sqrt{AP^2 + (33 - CP)^2}[/tex] Substituting PM into the equation, we get[tex]\text{Cost} = 4CP + 5 \cdot \sqrt{9^2 + (33-CP)^2}[/tex]

To minimize the cost, we take the derivative of the cost function and set it equal to 0 to find the critical points. Solving this equation will give you the value of CP that minimizes cost. Hence, by substituting found CP back to the original cost formula, we can find the minimal cost of installing the cable.

Learn more about Calculus Optimization here:

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The graph shows the solution for which inequalities?

Answers

Answer:

The answer is c

Step-by-step explanation:

the graph shows the equations y=3x-2 and y=1/2+3 and if y is greater than the otherside you shade above and if it's less than the otherside you shade below. y=3x-2 is sahded above the line and y=1/2+3 is shaded below the line.

Answer:

  see below

Step-by-step explanation:

The line with the shallow slope has a slope of 1 unit of rise for each 2 units of run, so a slope of 1/2. It has a y-intercept of 3. The shading is below it, so you're looking for an inequality that looks like ...

  y ≤ 1/2x + 3

Only one answer choice matches.

The mean monthly food budget for 39 residents of the local apartment complex is $419. What is the best point estimate for the mean monthly food budget for all residents of the local apartment complex?

Answers

Answer:

The best point estimate for the mean monthly food budget for all residents of the local apartment complex is $419.

Step-by-step explanation:

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean [tex]\mu[/tex] and standard deviation [tex]\sigma[/tex], the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean [tex]\mu[/tex] and standard deviation [tex]s = \frac{\sigma}{\sqrt{n}}[/tex].

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

In this problem:

The mean of the sample is $419.

What is the best point estimate for the mean monthly food budget for all residents of the local apartment complex?

By the Central Limit Theorem(inverse, that is, sample to the population), $419.

The best point estimate for the mean monthly food budget for all residents of the local apartment complex is $419.

A marketing consultant was hired to visit a random sample of five sporting goods stores across the state of California. Each store was part of a large franchise of sporting goods stores. The consultant taught the managers of each store better ways to advertise and display their goods.
The net sales for 1 month before and 1 month after the consultant's visit were recorded as follows for each store (in thousands of dollars):

Before visit: 57.1 94.6 49.2 77.4 43.2
After visit: 63.5 101.8 57.8 81.2 41.9

Do the data indicate that the average net sales improved? (Use a= 0.05)

Answers

Answer:

[tex]t=\frac{\bar d -0}{\frac{s_d}{\sqrt{n}}}=\frac{4.94 -0}{\frac{3.901}{\sqrt{5}}}=2.832[/tex]

[tex]df=n-1=5-1=4[/tex]

[tex]p_v =P(t_{(4)}>2.832) =0.0236[/tex]

We see that the p value is lower than the significance level of 0.05 so then we have enough evidence to reject the null hypothesis and we can conclude that the average net sales improved

Step-by-step explanation:

Let put some notation  

x=test value before , y = test value after

x: 57.1 94.6 49.2 77.4 43.2

y: 63.5 101.8 57.8 81.2 41.9

The system of hypothesis for this case are:

Null hypothesis: [tex]\mu_y- \mu_x \leq 0[/tex]

Alternative hypothesis: [tex]\mu_y -\mu_x >0[/tex]

The first step is calculate the difference [tex]d_i=y_i-x_i[/tex] and we obtain this:

d: 6.4, 7.2, 8.6, 3.8, -1.3

The second step is calculate the mean difference  

[tex]\bar d= \frac{\sum_{i=1}^n d_i}{n}=4.94[/tex]

The third step would be calculate the standard deviation for the differences, and we got:

[tex]s_d =\frac{\sum_{i=1}^n (d_i -\bar d)^2}{n-1} =3.901[/tex]

The next step is calculate the statistic given by :

[tex]t=\frac{\bar d -0}{\frac{s_d}{\sqrt{n}}}=\frac{4.94 -0}{\frac{3.901}{\sqrt{5}}}=2.832[/tex]

The next step is calculate the degrees of freedom given by:

[tex]df=n-1=5-1=4[/tex]

Now we can calculate the p value, since we have a right tailed test the p value is given by:

[tex]p_v =P(t_{(4)}>2.832) =0.0236[/tex]

We see that the p value is lower than the significance level of 0.05 so then we have enough evidence to reject the null hypothesis and we can conclude that the average net sales improved

An old house in Pomona, CA is inhabited by a variety of ghosts. Ghost appearances occur in the house according to a Poisson process having a rate of 1.4 ghosts per hour. A professor from Cal Poly Pomona has developed a device that can be used to detect ghost appearances. Suppose it is now 1:00 p.m. and the last ghost appearance (the 6th overall) was at 12:35 p.m.
What is the probability that the 7th ghost will appear before 1:30 p.m., to the nearest three decimal places?

Answers

Answer:

The probability is 0.503

Step-by-step explanation:

If the ghost appearances occur in the house according to a Poisson process with mean m, the time between appearances follows a exponential distribution with mean 1/m. so, the probability that the next ghost appearance happens before x hours is equal to:

[tex]P(X\leq x)=1-e^{-xm}[/tex]

Then, replacing m by 1.4 ghosts per hour we get:

[tex]P(X\leq x)=1-e^{-1.4x}[/tex]

Additionally, The exponential distribution have a memoryless property, so if it is now 1:00 p.m. and we want the probability that ghost appear before 1:30 p.m., we need to find the difference in hours from 1:00 p.m and 1:30 p.m. no matter that the last ghost appearance was at 12:35 p.m.

Therefore, there are 0.5 hours between 1:00 p.m. and 1:30 p.m, so the probability that the 7th ghost will appear before 1:30 p.m is calculated as:

[tex]P(x\leq 0.5)=1-e^{-1.4*0.5} =0.503[/tex]

Final answer:

The probability that the 7th ghost will appear before 1:30 p.m. in an old house in Pomona, CA can be calculated as approximately 0.5034, or 50.34%. This calculation is based on the Poisson distribution, with a rate of 1.4 ghosts per hour and the last ghost appearance occurring at 12:35 p.m.

Explanation:

The probability of the 7th ghost appearing before 1:30 p.m. can be calculated using the Poisson distribution. We know that the rate of ghost appearances is 1.4 ghosts per hour, which means the average time between ghost appearances is 1/1.4 hours. From 12:35 p.m. to 1:00 p.m., there are 25 minutes, or 25/60 hours. So, the probability that the 7th ghost will appear before 1:30 p.m. is equal to the probability that there will be at least 1 ghost in the remaining time, i.e., the probability that at least one ghost appears in the next 30 minutes.

We can use the complementary probability method to calculate this. The complementary probability is the probability that none of the ghosts appears in the next 30 minutes. Since the time follows a Poisson process, we can use the Poisson probability formula. Let's calculate:

Calculate the average rate of ghost appearances in the next 30 minutes:Rate = (1.4 ghosts/hour) * (30/60 hours) = 0.7 ghostsCalculate the probability of no ghost appearing:P(X = 0) = (e^(-0.7) * 0.7^0) / 0! = e^(-0.7) ≈ 0.4966Calculate the complementary probability:P(at least 1 ghost) = 1 - P(no ghost) = 1 - 0.4966 ≈ 0.5034

Therefore, the probability that the 7th ghost will appear before 1:30 p.m. is approximately 0.5034, or 50.34%.

The function ​R(x)equals108 StartRoot x EndRoot gives the total revenue per year in thousands of dollars generated by a small business having x employees. Use this function to evaluate ​R(12​)minus​R(11​). If the salary for the twelfth employee is $ 26 comma 000​, is it a good decision to hire the twelfth ​employee?

Answers

Answer:

Step-by-step explanation:

We are given that [tex] R(x) = 108\sqrt[]{x}[/tex] is the revenue for having x employees.

Let us calculate the following

[tex]R(12)-R(11) = 108\sqrt[]{12}-108\sqrt[]{11} = 15.93[/tex] REcall that is amount represents the revenue that having one extra employee would have.

We have that the salary of the 12th employee would be 26000. One criteria to define if it's a good idea to hire the 12th employee is to check if the profit for having an extra employee is positive. We will take the revenue of the extra employee minus the cost and check if it is positiv. Then,

[tex](108\sqrt[]{12}-108\sqrt[]{11})\text{(revenue for 12 employees)}-26000\text{(cost for the 12th employee} =-25984<0[/tex]

Since it is a negative amount, this means that it would be more expensive to have one extra employee than the revenue it would generate. Therefore, it won't be suitable to hire the 12th employee

What is the first step in solving 2x=y X+y=30

Answers

Answer: x = 10 y=20

Step-by-step explanation:

You can answer this question by plugging in each equation:

2x=y, x+y=30. Let us plug y as 2x in the second equation x+y=30

x+2x= 30

3x= 30

x=10

After we found x we can then find y by plugging the 10 for x.

2(10) = y

y =20

or you could plug in the other equation

10+y=30

subtract 10 from 30 and we get 20

to double check we can plug in both numbers

2(10) = 20 which is correct

and 10 + 20 = 30 which is correct

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