# Joint probability density help

#### teramerapyar

##### New member
Really stuck on this question. Help would be greatly appreciated.

Suppose that X is uniformly distributed on [0, 1] and that Y is uniformly distributed on
[0,X]. What is the joint density for X and Y ?

#### royhaas

##### Full Member
$$\displaystyle f(x,y) = f(y|x)f(x), 0<y<x<1$$.