25. A pharmaceutical company operates retail pharmacies in 10 eastern states. Recently, the company's internal audit department selected a random sample of n=300 prescriptions issued throughout the system. The objective of the sampling was to estimate the average dollar value of all prescriptions issued by the company. The data collected were x=$13.58 and s=3.00.

a. The 90% confidence interval estimate for the true average sales value for prescriptions issued by the company is from$enter your response here to $enter your response here.

(Round to the nearest cent- 2 decimal places. Use ascending order.)

You are asked to interpret the meaning of this confidence interval by choosing the correct answer below:

A.There is a 0.90 probability that the true mean prescription amount is between these two values.

B. The company believes that the true mean prescription amount falls between these two values 90% of the time.

C.The company believes with 90% confidence that the true mean prescription amount is between these two amounts.

D. The company believes with 90% confidence that the sample mean prescription amount is between these two amounts.

b. One of its retail outlets recently reported that it had monthly revenue of $6,916 from 517 prescriptions. Are such results to be expected? Should that retail outlet be audited?

(Round to the nearest cent as needed.)

When the population mean is at the upper limit of the 90% confidence interval computed in part a, the upper limit of the 90% confidence interval for the expected total monthly revenue for 517 prescriptions would be

$enter your response here.

When the population mean is at the lower limit of the 90% confidence interval computed in part a, the lower limit of the 90% confidence interval for the expected total monthly revenue for 517 prescriptions would be

$enter your response here.

Since this outlet reported sales of $6,916 from 517 prescriptions, there is no / good reason to believe that this is out of line. The retail outlet should / should not be audited.

26. A random sample of n measurements was selected from a population with unknown mean and standard deviation =20 for each of the situations in parts a through d. Calculate a 99% confidence interval for for each of these situations.

a. n=50, x=29

b. n=250, x=108

c.n=80, x=17

d. n=80, x=4.31

a. (enter your response here, enter your response here)

(Round to two decimal places as needed.)

b. (enter your response here,enter your response here)

(Round to two decimal places as needed.)

c. (enter your response here,enter your response here)

(Round to two decimal places as needed.)

d. (enter your response here,enter your response here)

(Round to two decimal places as needed.)

e. Since we are given =20 we should use the standard normal distribution to get the critical value

here.

A. True

B. False

28. Periodically, a town water department tests the the drinking water of homeowners for contaminants such as lead. The lead levels in water specimens collected for a sample of 10 residents of the town had a mean of

2.7 mg/L and a standard deviation of 2.9mg/L. Complete parts a through c.

a. Construct a 95% confidence interval for the mean lead level in water specimens from the town.

enter your response here, enter your response here

(Round to three decimal places as needed.)

b. Interpret the interval in terms of this application. Choose the correct answer below.

A. The water department can be 95% confident that the mean lead level in drinking water for all residents in the town is within this interval.

B. The water department is confident that 95% of the mean lead level in drinking water for all residents in the town is described by this interval.

C. The water department can be 95%confident that the mean lead level in drinking water for all residents in the town is 2.7mg/L.

D. The water department can be 5% confident that the mean lead level in drinking water for all residents in the town is within this interval.

E. The water department can be 95% confident that the mean lead level in drinking water for all residents in the town is outside this interval.

c. The phrase "95% confidence interval" means that if many intervals were constructed using the same methods and with the same sample size then enter your response here% of these intervals would contain the true value of which of the following choices?

A.Standard error

B.Sample mean

C. Standard deviation

D. Population mean

29. A manufacturing company produces electric insulators. You define the variable of interest as the strength of the insulators. If the insulators break when in use, a short circuit is likely. To test the strength of the insulators, you carry out destructive testing to determine how much force is required to break the insulators. You measure force by observing how many pounds are applied to the insulator before it breaks. The data shown below represent the amount of force required to break a sample of 30 insulators. Complete parts a through c below.

4	10	9	9	18	22	23	21	24	34
20	29	27	24	35	30	34	32	42	56
4	4	43	42	16	22	22	24	22	25

a.	Construct a 90% confidence interval for the population mean force.

enter your response here enter your response here

(Round to two decimal places as needed.)

30. In a survey of 1,200 organizations, 710 responded that "the need for collaboration among an increasing number of locations" is a business driver that led them to implement cloud solutions. Construct a 95% confidence interval estimate for the population proportion of organizations that indicated "the need for collaboration among an increasing number of locations" is a business driver that led them to implement cloud solutions.

A 95% confidence interval estimate for the population proportion is enter your response hereenter your response here.

(Round to four decimal places as needed.)

31. According to recent study, 173 of 490 technology CEOs from around the world responded that technological advances will transform their business and 92 responded that resource scarcity and climate change will transform their business. Complete parts (a) through (c) below.

a. Construct a 90% confidence interval estimate for the population proportion of tech CEOs who indicate technological advances as one of the global trends that will transform their business.

enter your response here enter your response here

(Round to four decimal places as needed.)

32. Most analysts focus on the cost of tuition as the way to measure the cost of a college education. But incidentals, such as textbook costs, are rarely considered. A researcher at Drummand University wishes to estimate the textbook costs of first-year students at Drummand. To do so, she monitored the textbook cost of 250 first-year students and found that their average textbook cost was $600 per semester. Identify the population of interest to the researcher.

A. All Drummand University students.

B. All first-year Drummand University students.

C. The 250 students that were monitored.

D. All college students.

34. In a survey, people were asked whether they thought sun went around the planet Earth or vice versa. Of

1924 people, 271 thought the sun went around Earth.

a. What proportion of people in the survey believed the sun went around Earth?

b. Find a 95% confidence interval for the proportion of all people with this belief.

c. Suppose a scientist said that 25% of people in the general population believe the sun goes around Earth. Using the confidence interval, would you say that was plausible? Explain your answer.

a. The proportion of people in the survey who believed the sun went around Earth is enter your response here.

(Round to three decimal places as needed.)

b. The 95% confidence interval is enter your response here, enter your response here.

(Round to three decimal places as needed.)

c. Is the scientist's claim that 25% of people in the general population believe the sun goes around Earth plausible?

Yes, it is / No, it is not plausible, since the value enter your response here is not inside / inside of the confidence interval.

(Type an integer or a decimal. Do not round.)

35. You are given the sample mean and the population standard deviation. Use this information to construct the 90% and 95% confidence intervals for the population mean. Interpret the results and compare the widths of the confidence intervals. If convenient, use technology to construct the confidence intervals.

36. A random sample of 60 home theater systems has a mean price of $124.00. Assume the population standard deviation is $16.10.

Construct a 90% confidence interval for the population mean.

The 90% confidence interval is (enter your response here, enter your response here).

(Round to two decimal places as needed.)

Construct a 95% confidence interval for the population mean.

The 95% confidence interval is (enter your response here,enter your response here).

(Round to two decimal places as needed.)

Interpret the results. Choose the correct answer below.

A. With 90% confidence, it can be said that the sample mean price lies in the first interval. With 95% confidence, it can be said that the sample mean price lies in the second interval. The 95% confidence interval is wider than the 90%.

B. With 90% confidence, it can be said that the population mean price lies in the first interval. With 95% confidence, it can be said that the population mean price lies in the second interval. The 95% confidence interval is narrower than the 90%.

C. With 90% confidence, it can be said that the population mean price lies in the first interval. With 95% confidence, it can be said that the population mean price lies in the second interval. The 95% confidence interval is wider than the 90%.

36. You are given the sample mean and the population standard deviation. Use this information to construct the 90% and 95% confidence intervals for the population mean. Interpret the results and compare the widths of the confidence intervals. From a random sample of 42 business days, the mean closing price of a certain stock was $109.23. Assume the population standard deviation is $10.66.

The 90% confidence interval is (enter your response here, enter your response here).

(Round to two decimal places as needed.)

The 95% confidence interval is (enter your response here, enter your response here).

(Round to two decimal places as needed.)

Which interval is wider? Choose the correct answer below.

A. The 95% confidence interval

B. The 90% confidence interval

Interpret the results.

A. You can be certain that the closing price of the stock was within the 90% confidence interval for approximately 38 of the 42 days, and was within the 95% confidence interval for approximately 40 of the

42 days.

B. You can be 90% confident that the population mean price of the stock is between the bounds of the 90% confidence interval, and 95% confident for the 95% interval.

C. You can be 90% confident that the population mean price of the stock is outside the bounds of the 90% confidence interval, and 95% confident for the 95% interval.

D. You can be certain that the population mean price of the stock is either between the lower bounds of the 90% and 95% confidence intervals or the upper bounds of the 90% and 95% confidence intervals.

37. You are given the sample mean and the population standard deviation. Use this information to construct the 90% and 95% confidence intervals for the population mean. Interpret the results and compare the widths of the confidence intervals. From a random sample of 56 dates, the mean record high daily temperature in a certain city has a mean of 85.38F. Assume the population standard deviation is 13.93F.

The 90% confidence interval is (enter your response here, enter your response here).

(Round to two decimal places as needed.)

The 95% confidence interval is (enter your response here,enter your response here).

(Round to two decimal places as needed.)

Which interval is wider? Choose the correct answer below.

A. The 90% confidence interval

B. The 95% confidence interval

Interpret the results.

A. You can be 90% confident that the population mean record high temperature is between the bounds of the 90% confidence interval, and 95% confident for the 95% interval.

B. You can be 90% confident that the population mean record high temperature is outside the bounds of the 90% confidence interval, and 95% confident for the 95% interval.

C. You can be certain that the mean record high temperature was within the 90% confidence interval for approximately 50 of the 56 days, and was within the 95% confidence interval for approximately 53

of the 56 days.

D. You can be certain that the population mean record high temperature is either between the lower bounds of the 90% and 95% confidence intervals or the upper bounds of the 90% and 95% confidence intervals.