HW9_skeleton

9.2

• 1. decreases
• 2. False
• 3. a
• 4. True
• 5. False
• 6. Robust
• 1. t = 1.316

  2. t = 1.697

  3. t = - 2.552

  4. t = 1.725

• 1. t = 2.205

  2. t = 1.309

  3. t = - 1.943

  4. t = 2.120

• 13. x-bar = 21; E = 3
• 14. x-bar = 25; E = 5
• 1. (103.66, 112.34)

  2. (101.13, 114.87); Decreasing the sample size increases the margin of error, E

  3. (104.58, 111..42); Decreasing the level of confidence decreases the margin of error, E

  4. No because the sample size would not be large enough.

• 1. Wrong, mplies the population mean varies

  2. Correct

  3. Wrong, focuses on the adult Americans instead of the mean

  4. Wrong, interretation should be about adult Americans, not adults in Idaho

• 29. (317.63, 394.57); We are 95% confident that the mean number of licks it takes to get to the center of a Tootsie Pop is between 317.63 and 394.57
• 30. (12.05, 14.75); We are 99% confident that the mean number of books that Americans have read in the past year is between 12.05 and 14.75.

9.3

• 1. False
• 2. True
• 3. False
• 4. False
• 5. x-squared 0.95 = 10.117, x-squared 0.05 = 30.144
• 6. x-squared 0.975 = 12.410, x-squared 0.025 = 39.364
• 1. (7.94, 23.66)

  2. (8.59, 20.63); Increasing the sample size, decreases the width of the interval.

  3. (6.61, 31.36); Increasing the level of confidence, increases the width of the interval.

• 11. (0.226, 0.542); We are 95% confident that the standard deviation of the pH of rainwater in Tucker County, West Virginia is between 0.226 and 0.542.