1) A statistics teacher wants to see if there is any difference in the abilities of students enrolled in statistics today and those enrolled five years ago. Final examination scores from a random sample of students enrolled today and from a random sample of students enrolled five years ago were selected. You are given the following information.

	Today	Five Years Ago
x	81	89
2	137.5	318.5
n	55	49

The p-value for determining if there is a difference between the two population means (Today - Five Years Ago) is _____.

a. 0.0077

b. 0.9923

c. 0.0038

d. 0.4962

2)Exhibit 15-5 Below is a partial Excel output based on a sample of 25 observations.

	Coefficients	Standard Error
Intercept	145.321		48.682
x1	25.625		9.150
x2	5.720		3.575
x3	0.823		0.183

Carry out the test of significance for the parameter ₁ at the 5% level. The null hypothesis should _____.

a. be rejected

b. be retested

c. not be rejected

d. be revised

3)Exhibit 10-3 A statistics teacher wants to see if there is any difference in the abilities of students enrolled in statistics today and those enrolled five years ago. Final examination scores from a random sample of students enrolled today and from a random sample of students enrolled five years ago were selected. You are given the following information.

	Today	Five Years Ago
x	82	88
2	112.5	54
n	45	36

Refer to Exhibit 10-3. The 95% confidence interval for the difference between the two population means is _____.

a. -24.228 to 12.23

b. -9.92 to -2.08

c. -13.84 to 1.84

d. -3.92 to 3.92

4)The 99% confidence interval estimate for a population variance when a sample standard deviation of 13 is obtained from a sample of 10 items is _____.

a. 67.09 to 783.91

b. 50.87 to 691.68

c. 64.48 to 876.70

d. 8.03 to 29.61