10.3

1.

  1. 2.602

  2. -1.729

  3. +/-2.179

2.

  1. 1.321

  2. -2.426

  3. +/-2.738

3.

  1. -1.379

  2. -1.714

  3. skip

  4. Since it is left tailed and the test statistic is greater than the critical value, there is not enough information to reject the null hypothesis.

4.

  1. 2.674

  2. 1.318

  3. skip

  4. Since the test statistic lies in the critical region we reject the null hypothesis.

5.

  1. 2.502

  2. -2.819, 2.819

  3. skip

  4. Since the test statistic is between the critical values there is not enough information to reject the null hypothesis.

  5. Lower bound: 99.39. Upper bound: 110.21. Since the 99% confidence interval includes 100 we do not reject the statement within the null hypothesis.

11.

Ho: $67

H1: >$67

  1. Since there is a 0.02 probability of getting a sample mean of 73+ dollars from a population with a mean of 67 dollars, we would expect 2 samples to result in a sample mean of 73+ dollars if we got 100 simple random samples with a size of 40 from a population whose mean is 67 dollars.

  2. Since the p value is lower than the alpha we reject the null hypothesis.

13.

Ho: 22

H1: >22

  1. The sample is random, the population is normally distributed, the sample is small relative to the population, and the sample values are independent of each other.

  2. The test statistic is greater than the critical value so we reject the null hypothesis.

  3. There is enough evidence to conclude that students who complete their curriculum are scoring above 22 on the math section.

15.

Test statistic: 4.553. We reject the null hypothesis meaning the mean hippocampal volume in alchoholic adolscents is less than the mean volume of 9.02.

17.

Test statistic: 0.813. We do not reject the null hypothesis meaning it is unlikely to get a mean credit score of 714.2+.

19.

Lower bound: 35.44 years. Upper bound: 42.36 years.There is not enough evidence to conclude that the mean age of a death-row inmate has changed since 2002 because the interval includes 40.7 years.

10.4

1.

  1. 28.869

  2. 14.041

  3. 16.047, 45.722

3.

  1. 20.496

  2. 13.091

  3. Skip but feel free to sketch on a piece of paper for your benefit.

  4. Since the test statistic is greater than the critical value we do not reject the null hypothesis.

13. Feel free to use any method you want. If you use the classical method please report the value of your test statistic and your decision. Likewise if you use the pvalue method please state your pvalue and your decision. Hint: The sample standard deviation (s) is 15.20.

Test statistic: 6.422. Critical value: 3.325. Since there is not enough information to conclude that the standard deviation is less than 18 seconds, we do not reject the null hypothesis.

15. Feel free to use any method you want. If you use the classical method please report the value of the test statistic and your decision. Likewise if you use the pvalue method please state your pvalue and your decision.

Test statistic: 15.639. Critical value: 15.659. Since the test statistic is lower than the critical value, we reject the null hypothesis.