if i'm given the expected value and standard deviation of a data set X and the exp. value and std. deviation of a data set Y, how do i find the standard deviation of X-Y?

10/19/2008 8:42:15 PM

If I remember this correctly, assuming X and Y are independent...

VAR(X-Y) = (1)^2*VAR(X) + (-1)^2*VAR(Y). Then just take the square root to find SD(X-Y).

10/19/2008 8:50:28 PM

i believe that works. thanks a lot man.

10/19/2008 9:11:41 PM