If we are testing for the difference between the means of 2 independent populations presuming equal variances with samples of n1 = 20 and n2 = 20, the number of degrees of freedom is equal to a. 38. b. 19. c. 18. d. 39.

Null hypothesis:

Alternative hypothesis:

And for this case we assume that we have equal variances so that means:

For this case the degrees of freedom are given by:

And replacing we got:

And the best answer would be:

a. 38

Step-by-step explanation:

For this problem we want to test the following:

Null hypothesis:

Alternative hypothesis:

And for this case we assume that we have equal variances so that means:

For this case the degrees of freedom are given by:

And replacing we got:

And the best answer would be:

a. 38