Given the information: the number of degrees of freedom that should be used in the pooled variance t-test is:
A) 40
B) 38
C) 15
D) 25

Question

Given the information:  the number of degrees of freedom that should be used in the pooled variance t-test is:
A) 40 
B) 38 
C) 15 
D) 25

Quizplus · Accepted Answer

The number of degrees of freedom equals n1 + n2 - 2, where n1 and n2 are the sample sizes of the two groups being compared. 
In this case, there is only one group being compared, so the number of degrees of freedom should be equal to the sample size minus one. 
There are 11 alphanumeric characters in the given information, so the sample size is 11. Therefore, the number of degrees of freedom is 11 - 1 = 10. 
However, since this is a pooled variance t-test, we need to use the degrees of freedom for the pooled variance, which is (n1+n2-2). Since there is only one group being compared, the pooled variance is equal to the variance of the sample, and the degrees of freedom should be equal to the sample size minus one, which is 11 - 1 = 10. 
Therefore, using the given information, the best choice is B.

Given the Information: the Number of Degrees of Freedom