8.1

15

  1. The sampling distribution of x is normally distributed, with a center at 80 and a spread of 2.

  2. .0668

  3. .0179

  4. .7969

17

  1. The sampling distrution of x is normally distributed, with a center at 64 and a spread of 4.907.

  2. .7486

  3. .4052

19

  1. .3520

  2. The sampling distribution is normally distributed, with a center at 266 and a spread of 3.578.

  3. .0465

  4. .0040

  5. The larger the random sample, the more likely it is to have an outcome of 260 days or less.

  6. .9844

21

  1. .3085

  2. .0418

  3. .0071

  4. The greater the sample size, the smaller the probability there is of having a mean greater then 95.

  5. .1056

  6. x = 93.7 23

  7. .5675

  8. .7291

  9. .8051

  10. .8531

  11. The likelihood of earning a positive rate of return on stocks increases as the investment time horizon increases. Therefore, there is a positive correlation.

8.2

11

  1. The sampling distribution is normally distributed, with a center at .8 and a spread of .046.

  2. .1922

  3. .0047

12

  1. The sampling distribution is normally distributed with a center at .65 and a spread of .0337.

  2. .1867

  3. .0384

13

  1. The sample distribution is noramlly distributed with a mean of .35 and a spread of .0151

  2. .0040

  3. .0233

14

  1. The sample distribution is normally distributed with a center at .42 and a spread of .0129.

  2. .0102

  3. .6060

15

  1. The response is qualitative.

  2. The sample proportion is a random variable because it is a proportion of one sample.

  3. The sample distribution is normally distributed with a mean of .47 and a spread of .0353.

  4. .1977

  5. .0239

16

  1. The response is qualitative.

  2. The sample proportion is a random variable because it is a proportion of one sample.

  3. The sample is normally distributed with a center at .82 and a spread of .0384.

  4. .2177

  5. This is unusual because the probability is .03 which is less than .05.

17

  1. The sample distribution is noramlly distributed with a mean of .39 and a spread of .0218.

  2. .3228

  3. .3198

  4. This is not unusual because the probability is .08 which is greater then .05.