Originally Posted by

**hitman** I see,, I think I got the idea, I am going to play with it.

Another question, about F-distribution, lets say $\displaystyle w \sim F(4,5)$ now we want to find a and b such that $\displaystyle P(W> a) = 0.05 = P(W<b)$

This question is not clear for me. $\displaystyle p(w>a) = 0.05$ is easy. you calculate the degree of freedom, look into the table for 3,4 and 0.05 and you find a. However, I am not sure about the next part. is it like:

$\displaystyle p(w<b) = 1- p(w>b) \rightarrow p(w>b) = 0.95 $

and probably to find 0.95 I have to use statistic software Mr F says: Yes, you do.