Two samples, one of size 14 and the second of size 13, are selected to test the difference between two population means. How many degrees of freedom are used to find the critical value

25 Degrees of Freedom

Explanation:

Significance of difference between two population means (based on sample means) is done with formula : √ [ (Σx1^2 + Σx2^2 / N1 + N2 - 2) (1/N1 + 1/N2) ]

with degrees of freedom = N1 + N2 - 2

= 14 + 13 - 2

= 25