8.1

15

  1. approximately normal 80, 2

  2. .0668

  3. 0.0179

  4. .7969

17

  1. it must be a random sample and must be independent, if these conditions are true, the sampling distrubution is exactly normal. 64.097

  2. .7486

  3. .4052 19

  4. 0.3520

  5. normally distrubuted , 266, 3.578

  6. .0465

  7. .0040

  8. The sample likely came from a population whose mean gestation period was less than 266 days

  9. .9844

21

  1. 0.3085

  2. .0418

  3. .0071

  4. Increasing the sample size decreases the population

  5. A mean reading rate of 92.8 is not unusual indicating that the new program is not more effecive than the old program

  6. There is a 5% chance that the mean reading speed of a random sample of a second grade student will exceed 93.7 wpm

23

  1. .5675

  2. .7291

  3. .8051

  4. .8531

  5. the likelihood of earning a postive rate of return increases as the investment time increases

8.2

11

  1. P(75)~ 10,000(.8, .0462)

  2. .1922

  3. .0047

12

  1. P(200) ~ 25,000(.65, .0337)

  2. .1867

  3. .0375

13

  1. P(1000)~ 25,000 (.65,.0337)

  2. .0040

  3. .0233

14

  1. P(1460)~ 1,500,000 (.42, .0129)

  2. .0102

  3. .0239

15

  1. qualitative with two possible outcomes

  2. variability is in the individuals because they chose what langauge to order the meal in

  3. the sample is normal .0305.

  4. .1977

  5. .0239

16

  1. qualitative

  2. P(100) ~ 100(.82, .0384)

  3. the source of variability is the indivduals in the survey and whether or not they are satisfied with their lives

  4. .2177

  5. This result is unusual

17

  1. the sample is normal .022

  2. .3228

  3. .3198

  4. .0838