# Business Statistics 3rd Edition By Sharpe – Test Bank

Chapter 11: Confidence Intervals and Hypothesis Tests for Means – Quiz C

– Multiple Choice Name ________________________________________

11.2.1 Examine the sampling distribution of the mean.

1. In a metal fabrication process, metal rods are produced to a specified target length of

15 feet. Suppose that the lengths are normally distributed. A quality control specialist

collects a random sample of 16 rods and finds the sample mean length to be 14.8 feet and

a standard deviation of 0.65 feet. Which of the following statements is true?

A. The sampling distribution for the sample mean follows the t-distribution with 16

degrees of freedom.

B. The sampling distribution for the sample mean follows the t-distribution with 15

degrees of freedom.

C. The mean of the sampling distribution for the sample mean is 14.8 feet.

D. The sampling distribution for the sample mean is Normal with a mean of 14.8 feet

and standard deviation of .65 feet.

E. The standard error is 0.65 feet.

11.3.3 Calculate and describe the standard error of the mean.

2. In a metal fabrication process, metal rods are produced to a specified target length of

15 feet. Suppose that the lengths are normally distributed. A quality control specialist

collects a random sample of 16 rods and finds the sample mean length to be 14.8 feet and

a standard deviation of 0.65 feet. The standard error of the mean is

A. 0.65 ft.

B. 0.346 ft.

C. 0.1625 ft.

D. 0.0098 ft.

E. 1.625 ft.

11.5.6 Create and interpret confidence intervals for the mean.

3. In a metal fabrication process, metal rods are produced to a specified target length of

15 feet. Suppose that the lengths are normally distributed. A quality control specialist

collects a random sample of 16 rods and finds the sample mean length to be 14.8 feet and

a standard deviation of 0.65 feet. The 95% confidence interval for the true mean length

of rods produced by this process is

A. 14.544 to 15.056 ft.

B. 14.345 to 15.255 ft.

C. 13.912 to 15.688 ft.

D. 14.454 to 15.146 ft.

E. 13.834 to 15.766 ft.

11.4.5 Find critical values of t.

4. A manufacturer of cheese filled ravioli supplies a pizza restaurant chain. Based on

data collected from its automatic filling process, the amount of cheese inserted into the

ravioli is normally distributed. To make sure that the automatic filling process is on

target, quality control inspectors take a sample of 25 ravioli. The correct value of t

*

to

construct a 98% confidence interval for the true mean amount of cheese filling is

A. 2.492

B. 3.467

C. 2.797

D. 2.064

E. 3.745

11.5.6 Create and interpret confidence intervals for the mean.

5. A manufacturer of cheese filled ravioli supplies a pizza restaurant chain. Based on

data collected from its automatic filling process, the amount of cheese inserted into the

ravioli is normally distributed. To make sure that the automatic filling process is on

target, quality control inspectors take a sample of 25 ravioli and measure the weight of

cheese filling. They find a sample mean weight of 15 grams with a standard deviation of

1.5 grams. What is the margin of error at 90% confidence?

A. 0.3 grams

B. 0.5133 grams

C. 0.8391 grams

D. 1.5 grams

E. 0.06 grams

11.7.8 Perform hypothesis tests for means.

6. A pharmaceutical company wants to answer the question whether it takes longer than

45 seconds for a drug in pill form to dissolve in the gastric juices of the stomach. A

sample was taken from patients taken the given drug in pill form and times for the pills to

be dissolved were measured. State the hypotheses to test this question.

A. H : = 45sec; H : > 45sec 0 A μ μ

B. sec H0 : μ > 45sec;HA : μ ≤ 45

C. sec H0 : μ = 45sec;HA : μ ≤ 45

D. 0 45 45 H : sec;H : sec μ ≥ A μ <

E. sec

11.6.7 Check assumptions and conditions for inference.

7. A pharmaceutical company wants to answer the question whether it takes longer than

45 seconds for a drug in pill form to dissolve in the gastric juices of the stomach. A

sample was taken from patients taken the given drug in pill form and times for the pills to

be dissolved were measured. b. State assumptions of the test.

A. The subjects must be part of a medical study group investigating the drug.

B. The subjects in the sample must be randomly selected from a population.

C. B and D are required conditions.

D. The sample data must come from a normally distributed population of observations for

the variable under study.

E. None of the above.

11.5.6 Create and interpret confidence intervals for the mean.

8. A manufacturer of cheese filled ravioli supplies a pizza restaurant chain. Based on

data collected from its automatic filling process, the amount of cheese inserted into the

ravioli is normally distributed. To make sure that the automatic filling process is on

target, quality control inspectors take a sample of 25 ravioli and measure the weight of

cheese filling. They find the 99% confidence interval of 14.16 to 15.84 grams. Which of

the following is the correct interpretation?

A. We are 99% confident that the mean weight of cheese filling in all ravioli made by this

process is between 14.16 and 15.84 grams.

B. 99% of all ravioli made by this process will have cheese filling weights between 14.16

and 15.84 grams.

C. The weight of cheese filling in the ravioli is between 14.16 and 15.84 grams 99% of

the time.

D. All of the above.

E. None of the above.

11.5.2 Determine sample sizes.

9. A manufacturer of cream filled donuts wants to make sure that its automatic filling

process is on target. Based on a sample of 25 donuts the mean weight of cream filling is

estimated to be 15 grams with a standard deviation of 1.5 grams. However, the quality

control inspectors wish to estimate the mean weight of cream filling more accurately so

that they can be 99% confident that it is within 0.25 grams of the true mean. How many

donuts should they sample?

A. 150

B. 543

C. 212

D. 410

E. 239

11.7.8 Perform hypothesis tests for means.

10. A pharmaceutical company wants to answer the question whether it takes longer than

45 seconds for a drug in pill form to dissolve in the gastric juices of the stomach. A

sample was taken from 8 patients taking the given drug in pill form and times for the pills

to be dissolved were measured. The mean was 45.212 sec for the sample data with a

standard error of 0.580. Determine the P-value for this test.

A. 0.181

B. 0.724

C. 0.649

D. 0.362

E. 0.366

Chapter 11: Confidence Intervals and Hypothesis Tests for Means – Quiz C – Key

1. B

2. C

3. D

4. A

5. B

6. A

7. C

8. A

9. E

10. D

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