# Thread: need help joint distribution

1. ## need help joint distribution

Can some help me with this?

f(x,y) = kxy 0<x<1; 0<y<1

0 else

If X and Y have a joint pdf

Find the value of k that makes f(x,y) to be a pdf
Find P(X<0.5, Y<0.75)

2. 1. You want $\int _0 ^1 \int _0 ^1 kxy : dy : dx = 1$. So you evaluate the integral and then solve for k.

2. Integrate $\int _0 ^{0.5} \int _0 ^{0.75} kxy : dy : dx$ for the k you found in part 1.

thanks