# Independent Random Variable (exponential function)

• Apr 27th 2010, 02:39 PM
atalay
Independent Random Variable (exponential function)
If the random variables X and Y have the joint pdf:

f (x, y)= { 2e^-x-y for 0<x<y, 0<y<∞
0, elsewhere

Show that X and Y are dependent.

• Apr 27th 2010, 03:56 PM
Anonymous1
Find the marginals and show that their product != f(x,y).

Do you know how to find the marginal distributions?

...You could also simply use a factorization argument.
• Apr 27th 2010, 04:29 PM
atalay
Yes, i know marginals, but i have a problem that i do not know integrals' lower limit and upper limit.
• Apr 27th 2010, 04:54 PM
Anonymous1
Quote:

Originally Posted by atalay
Yes, i know marginals, but i have a problem that i do not know integrals' lower limit and upper limit.

$\int_0^y$ and $\int_0^{\infty}...$
• Apr 27th 2010, 05:09 PM
atalay
i am thinking correctly but i do not trust me.

thank you.