HW9_skeleton

9.2

• 1. decreases
• 2. F
• 3. a
• 4. T
• 5. F
• 6. robust
• 1. t0.10=1.316

  2. t0.05=1.697

  3. t0.99=-2.552

  4. t0.05=1.725

• 1. t0.02=2.205

  2. t0.10=1.309

  3. t0.95==1.943

  4. t0.25=0.690

• 13. E=3, x-bar=21
• 14. E=5, x-bar=25
• 1. lower bound:103.656,upper bound:112.344

  2. lower bound:100.417,upper bound:115.583 decreasing the sample size increases the margin of error

  3. lower bound:104.578,upper bound:111.422 decreasing the level of confidence decreases the margin of error

  4. the population is too small to be compared

• 1. Flawed.This interpretation implies that the population mean varies rather than the interval

  2. correct

  3. Flawed.This interpretation makes an implication about individuals rather than the mean

  4. Flawed.This interpretation should be about the mean number of hours worked by adult Americans

• 29. lower bound:317.63licks, upper bound:394.57licks we are 95% confident the mean number of licks to the center of a Tootsie pop is between 317.63 and 394.57
• 30. lower bound:12.05, upper bound:14.75 we are 99% confident the mean number of books read by Americans in past year was between 12.05 to 14.75

9.3

• 1. F
• 2. T
• 3. F
• 4. F
• 5. X^2(0.95)=10.117, X^2(0.05)=30.144
• 6. X^2(0.975)=12.401, X^2(0.025)=39.364
• 1. lower bound:7.94, upper bound:23.66

  2. lower bound:8.59, upper bound:20.63 the width of the interval decreases

  3. lower bound:6.61, upper bound:31.36 the width of the interval increases

• 11. lower bound:0.226, upper bound:0.542 we can be 95% confident that the population strandard deviation of the ph of rainwater in Tucker country WV is between 0.226 and 0.542