27-29

t-Test: Two-Sample Assuming Unequal Variances
	class 1	class 2
Mean	78	79
Variance	90	47.333
Observations	9	7
Hypothesized Mean Difference	0
df	14
t Stat	-0.244
P(T<=t) one-tail	0.405
t Critical one-tail	1.761
P(T<=t) two-tail	0.811
t Critical two-tail	2.145

A) A sample of scores on an examination given in two different classes is examined. The following Excel output was obtained. Use = .05. In order to determine if Class 2 has a different grade from Class 1, what are the null and alternative hypotheses?

B) A sample of scores on an examination given in two different classes is examined. The following Excel output was obtained. Use = .05.Exactly what p-value did you use to answer to determine if Class 2 has a different average?

C) A sample of scores on an examination given in two different classes is examined. The following Excel output was obtained. Use = .05.Does Class 2 have a different grade?