8.1

15

  1. Approximately normal; 80, 2.

  2. 0.0668.

  3. 0.0179.

  4. 0.7969.

17

  1. It must be a random sample, and it must be independent.If this condition is trute the sampling distribution is exactly normal.64, 4.907.

  2. 0.7486.

  3. 0.4052.

19

  1. 0.3520.

  2. Normally distrubuted; 266, 3.578.

  3. 0.0465.

  4. 0.0040.

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

  6. 0.9844.

21

  1. 0.3085.

  2. 0.0418.

  3. 0.0071.

  4. It decreases the probabilty of x->95.

  5. This would not be unusual and shows that the new reading program is not more effective than the old program.

  6. 93.7 wpm.

23

  1. 0.5675.

  2. 0.7291.

  3. 0.8051.

  4. 0.8505.

  5. As the time horizon increases, the likelihood of a positve return increases.

8.2

11

  1. P(75)~10,000(0.8, 0.0462).

  2. 0.1922.

  3. .0047.

12

  1. P(200)~25,000(0.65, 0.0337).

  2. .1867.

  3. .0375.

13

  1. P(1000)~1,000,000(.35, 0.0151).

  2. 0.0040.

  3. 0.0239.

14

  1. P(1460)~1,500,000(.42, 0.0129).

  2. 0.0102.

  3. 0.0606.

15

  1. Qualitative.

  2. The source of the variability is the individuals in the survey and their ability to order a meal in a foreign language.

  3. P(200)~200(0.47, 0.0353).

  4. 0.1977.

  5. This result is unusal.

16

  1. Qualitative.

  2. P(100)~100(0.82, 0.0384).

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

  4. 0.2177.

  5. This result is unusual.

17

  1. P(500)~500(0.39, 0.0218).

  2. 0.3228.

  3. 0.3198.

  4. No, this would not be unusual.