8.1

15

  1. Normal distribution; mean is 80, standard error is 2

  2. 7%

  3. 2%

  4. 78%

17

  1. it must be normally distributed, and x-bar is normal

  2. 75%

  3. 41%

19

  1. 35%

  2. it would be normal

  3. 5%

  4. .4%

  5. the sample is from a population with a mean gestation period of less than 260 days

  6. 98%

21

  1. 31%

  2. 4%

  3. .7%

  4. it decreases the probability that x-bar will be greater than 95; it’s because the standard deviation of x-bar decreases as the population increases

  5. the new prrogram is not that much better than the old one

  6. 93.7

23

  1. 57%

  2. 73%

  3. 81%

  4. 85%

  5. positive rate increases as time horizon increases

8.2

11

  1. distribution is approximately normal with mean .8 and standard error .046

  2. 19%

  3. .5%

12

  1. distribution is approximately normal with mean .65 and standard error .034

  2. 19%

  3. 3.9%

13

  1. distribution is approximately normal with mean .35 and standard error .015

  2. .4%

  3. 2.3%

14

  1. distribution is approximately normal with mean .42 and standard error .014

  2. 1.4%

  3. 7.1%

15

  1. qualitative - they can or they can’t

  2. it varies from sample to sample; the variable is their ability to do it or not

  3. distribution is approximately normal with mean .47 and standard error .035

  4. 20%

  5. 2.4%

16

  1. qualitative - whether they’re happy or not

  2. it varies from sample to sample; the variable is whether they’re happy or not

  3. distribution is approximately normal with mean .82 and standard error .038

  4. 22%

  5. it would be unusual - the probability that would happen is very low

17

  1. distribution is approximately normal with mean .39 and standard error .022

  2. 32%

  3. 32%

  4. 8.4%