Chapter Exercises

CH. 10

31) The test statistic is z= (9 - 10) / (2.8 / sqrt (50) = -2.525

The P value is: P(z < -2.525) = 0.00578.

People in the program lose fewer than 10 pounds.

32) Use a z-test because we're given the standard deviation of the population:

Hypotheses:

H0: mu<=16

Ha: mu>16

The test statistic is:

z=(16.05-16)/(0.03/sqrt(50))= 11.785

The p-value is less than 0.0001, so we reject the null hypothesis. The mean is greater than 16.

38) H0: mu>= 6

Ha: mu<6

The sample statistics is:

average: 5.6375

standard deviation: 0.635

The test statistic is

t=(5.6375-6)/(0.635/sqrt(8)) = -1.615

There is not enough evidence to suggest that the mean is less than 6.

CH. 11

27) Hypotheses:

H0: mu1 = mu2

Ha: mu1 not equal to mu2

The test statistic is: z=(24.51 - 22.69)/sqrt(4.48^2/35+3.86^2/40) = 1.871

P-value = 0.0613

We do not reject the null hypothesis. There is not enough evidence to suggest that the means are equal at the .01 level of significance.

46) The sample statistics are:

Little River Mean: 27.461

Little River Standard deviation: 4.44

Little Rivver Variance: 19.717

Murrells Inlet Mean: 25.689

Murrells Inlet Standard deviation: 2.685

Murrells Inlet Variance: 7.207

H0: mu1 = mu2

Ha: mu1 not equal to mu2

df = (19.727/10 + 7.207/12)^2/((19.717/10)^2/9 + (7.207/12)^2/11) = 14.248

Critical Value = 2.131.

t=(27.461-25.689)/sqrt(19.717/10+7.207/12) = 1.105

We do not reject the null hypothesis. There is not enough evidence to suggest that the means are not the same.

52) Give the data in the Excel table, we do not reject the null hypothesis. There is not enough evidence to say that the means are unequal.

CH. 12

23) Hypotheses:

H0: sigma_oceanfront <= sigma_threeblocks

Ha: sigma_oceanfront > sigma_threeblocks

The critical value is from the F-table. The degrees of freedom are 20 and 17. The value is 3.16

The test...