Slide 7- 1Copyright © 2010, 2007, 2004 Pearson Education, Inc. All Rights Reserved.

MAT 155 Chapter 7 Estimates and Sample Sizes

The following is a brief review of Chapter 7. This does NOT cover all the material in that chapter.

Click on Slide Show and View Slide Show.Read and note your answer to the question.Advance the slide to see the answer.

Dr. Claude Moore, Math Instructor, CFCC

Slide 7- 2Copyright © 2010, 2007, 2004 Pearson Education, Inc. All Rights Reserved.

Find the critical value for zα/2 that corresponds to a degree of confidence of 98%.

A. 2.575

B. 2.33

C. 1.75

D. 2.05

Slide 7- 3Copyright © 2010, 2007, 2004 Pearson Education, Inc. All Rights Reserved.

Find the critical value for zα/2 that corresponds to a degree of confidence of 98%.

A. 2.575

B. 2.33

C. 1.75

D. 2.05

Slide 7- 4Copyright © 2010, 2007, 2004 Pearson Education, Inc. All Rights Reserved.

Find the margin of error for the 95% confidence interval used to estimate the population proportion with n = 163 and x = 96.

A. 0.0680

B. 0.0755

C. 0.132

D. 0.00291

Slide 7- 5Copyright © 2010, 2007, 2004 Pearson Education, Inc. All Rights Reserved.

Find the margin of error for the 95% confidence interval used to estimate the population proportion with n = 163 and x = 96.

A. 0.0680

B. 0.0755

C. 0.132

D. 0.00291

Slide 7- 6Copyright © 2010, 2007, 2004 Pearson Education, Inc. All Rights Reserved.

459 randomly selected light bulbs were tested in a laboratory, 291 lasted more than 500 hours. Find a point estimate of the true proportion of all light bulbs that last more than 500 hours.

A. 0.632

B. 0.366

C. 0.388

D. 0.634

Slide 7- 7Copyright © 2010, 2007, 2004 Pearson Education, Inc. All Rights Reserved.

459 randomly selected light bulbs were tested in a laboratory, 291 lasted more than 500 hours. Find a point estimate of the true proportion of all light bulbs that last more than 500 hours.

A. 0.632

B. 0.366

C. 0.388

D. 0.634

Slide 7- 8Copyright © 2010, 2007, 2004 Pearson Education, Inc. All Rights Reserved.

Use the confidence level and sample data to find the margin of error E.

College students’ annual earnings:

99% confidence, n = 74 x = $3967, σ = $874

A. $262

B. $9

C. $237

D. $1187

Slide 7- 9Copyright © 2010, 2007, 2004 Pearson Education, Inc. All Rights Reserved.

Use the confidence level and sample data to find the margin of error E.

College students’ annual earnings:

99% confidence, n = 74 x = $3967, σ = $874

A. $262

B. $9

C. $237

D. $1187

Slide 7- 10Copyright © 2010, 2007, 2004 Pearson Education, Inc. All Rights Reserved.

You want to be 95% confident that the sample variance is within 40% of the population variance. Find the appropriate sample size.

A. 224

B. 11

C. 14

D. 57

Slide 7- 11Copyright © 2010, 2007, 2004 Pearson Education, Inc. All Rights Reserved.

You want to be 95% confident that the sample variance is within 40% of the population variance. Find the appropriate sample size.

A. 224

B. 11

C. 14

D. 57

Slide 7- 12Copyright © 2010, 2007, 2004 Pearson Education, Inc. All Rights Reserved.

To find the standard deviation of the diameter of wooden dowels, the manufacturer measures 19 randomly selected dowels and finds the standard deviation of the sample to be s = 0.16. Find the 95% confidence interval for the population standard deviation σ.

A. 0.13 < σ < 0.22

B. 0.12 < σ < 0.24

C. 0.11 < σ < 0.25

D. 0.15 < σ < 0.21

Slide 7- 13Copyright © 2010, 2007, 2004 Pearson Education, Inc. All Rights Reserved.

To find the standard deviation of the diameter of wooden dowels, the manufacturer measures 19 randomly selected dowels and finds the standard deviation of the sample to be s = 0.16. Find the 95% confidence interval for the population standard deviation σ.

A. 0.13 < σ < 0.22

B. 0.12 < σ < 0.24

C. 0.11 < σ < 0.25

D. 0.15 < σ < 0.21