HW9_skeleton

9.2

• 1. decreases
• 2. false
• 3. alpha
• 4. 1/2
• 5. true
• 6. margin of error
• 1. 1.316

  2. 1.697

  3. -2.552

  4. 1.725

• 1. 2.205

  2. 1.309

  3. -1.943

  4. 1.746

• 13. x bar=21 E=3
• 14. x bar=25 E=5
• 1. lower bound: 103.7, upper bound: 112.3

  2. lower bound: 100.4, upper bound: 115.6 decreases margin of error

  3. lower bound: 104.6, upper bound: 111.4 decreases margin of error

  4. no - sample sizes too small

• 1. correct

  2. correct

  3. incorrect: talking about individuals rather than the mean

  4. incorrect: interpretation should be about the mean number of hours worked by adult americans, not about adults in Idaho

• 29. (317.63 licks, 394.57) we are 95% confident the mean # of licks to the center of a tootsie pop is between 317.63 and 394.57.
• 30. (12.05, 14.75) we are 99% confident the mean # of books that Americans read either all or part of during the preceding year is between 12.05 and 14.75.

9.3

• 1. false - skewed right
• 2. true
• 3. false
• 4. true
• 5. X^2 0.95=10.117 X^2 0.05=30.144

• 6.x^2 0.975= 8.231 x^2 0.025= 31.595

• 1. (7.94, 23.66)

  2. (8.59, 20.63)

  3. (6.61, 31.36)

• 11. (0.226,0.542) we are 95% confident that the population standard deviation of repair costs of a low impact bumper crash on a mini car is between 0.226 and 0.524