HW8_skeleton

9.1

• 1. Point estimate
• 2. Level of confidence, (1-alpha) x 100%
• 3. False
• 4. Critical value
• 5. Increases
• 6. Decreases
• 7. 1.645
• 8. 2.575
• 9. 2.326
• 10. 1.751
• 11. phat = 0.225, E = 0.024, x = 270
• 12. phat = 0.0625, E = 0.0115, x = 70
• 15. Lower bound = 0.146, upper bound = 0.254 (90% sure)
• 16. Lower bound = 0.319, upper bound = 0.481
• 1. The statement is incorrect because there was no given interval about the population proportion

  2. Statement is incorrect because the interpretation has different levels of confidence

  3. The statement is correct because there is a given interval for the population proportion

  4. The statement is incorrect because the interpretation assumes that this interval sets the standard for all other intervals, which is false

• 1. 0.181

  2. np(1-p) = 2306 x 0.181(1-0.181) = 341.84 is greater than 10

  3. Lower bound = 0.168, upper bound = 0.194

  4. We are 90% sure that the population proportion of adult Americans 18 or older who have donated blood within the past two years is between 0.168 and 0.194

• 1. 0.430

  2. np(1-p) = 1153 x 0.430(1-0.430) = 282.6 is greater than 10

  3. Lower bound = 0.401, upper bound = 0.459

  4. We are 95% sure that the population proportion of workers and retirees in the US over the age of 25 that had less than $10,000 in savings is between 0.401 and 0.459