If we are testing for the difference between the means of 2 independent populations presumes equal variances with samples of n1 = 20 and n2 = 20, the number of degrees of freedom is equal to

a) 39
b) 38
c) 19
d) 18.

38 dof

To calculate the number of degrees of freedom when testing for the difference between the means of two independent populations with equal variances, you can use the formula:

df = (n1 - 1) + (n2 - 1)

In this case, n1 = 20 and n2 = 20. Plugging these values into the formula, we get:

df = (20 - 1) + (20 - 1)
df = 19 + 19
df = 38

Therefore, the correct answer is b) 38.

To determine the degrees of freedom for the test comparing the means of two independent populations with equal variances, you can use the formula:

df = (n1 - 1) + (n2 - 1)

In this case, n1 = 20 and n2 = 20, so the degrees of freedom would be:

df = (20 - 1) + (20 - 1)
= 19 + 19
= 38

Therefore, the correct answer is b) 38.