10.3

1.

  1. 2.602

  2. -1.729

  3. -2.179, 2.179

2.

  1. 1.321

  2. -2.426

  3. -2.738

3.

  1. -1.379

  2. -1.714

  3. Skip this problem.

  4. Do not reject the null hypothesis because it is left-tailed and the test statistic is greater than the critical value.

4.

  1. 2.674

  2. 1.318

  3. Skip this problem.

  4. Reject the null hypothesis because it is right-tailed and the test statistic is greater than the critical value.

5.

  1. 2.502

  2. -2.819, 2.819

  3. Skip this problem.

  4. Do not reject the null hypothesis because it is two-sided and the test statistic is between the two critical values.

  5. (99.39,110.21); Do not reject the null hypothesis

11.

Ho: μ=$67

Ha: μ>$67

  1. There is a 0.02 probability of obtaining a sample mean of $73 or higher from a population whose mean is $67

  2. The p-value is less than α=0.05, so we reject the statement in the null hypothesis.

13.

Ho: μ=22

Ha: μ>22

  1. Sample is random. Sample size is large.

  2. 2.176>1.660, so we reject the null hypothesis.

  3. There is sufficient evidence to conclude that students who complete the core curriculum are scoring above 22 on the math portion of the ACT.

15.

Test statistic of -4.553 is less than critical value of -2.718, so we reject the null hypothesis.

There is sufficient evidence to conclude that the mean hippocampal volume in alcoholic adolescents is less than the normal mean volume of 9.02 cubic cm.

17.

Test statistic of 0.813 is less than the critical value of 1.685, so we do not reject the null hypothesis.

It is not unlikely to obtain a mean credit score of 714.2 or higher even though the true populaiton mean credit score is 703.5.

19.

(35.44,42.36)

There isn’t sufficient evidence to conclude that the mean age of death-row inmates has changed since 2002 because μ=40.7 is within the interval.

10.4

1.

  1. 28.869

  2. 14.041

  3. 16.047, 45.722

3.

  1. 20.496

  2. 13.091

  3. Skip this problem

  4. Do not reject the null hypothesis because it is left-tailed and the test statistic is greater than the critical value.

13.

Note. The sample standard deviation of the data shown is.\(15.205043\). You will have to knit this to see the number though.

6.422

Do not reject the null hypothesis. There isn’t sufficient evidence at α=0.05 level of significance to conclude that the standard deviation wait-time is less than 18.0 seconds.

15.

15.639

Reject the null hypothesis. There is sufficient evidence at α=0.10 level of significance to conclude that Rose is a more consistent player than other shooting guards in the NBA.