**Determine the value of c that makes the function ,f(x,y)=cxy a joint probability density function over the range 0 less than or equal to X less than or equal to 4 and 0 less than or equal to Y less than or equal to X. Then, determine the following;**

a) P(X<1,Y<2) b) P(1<X<2) c) P(Y>1) d)E(X)

**Answer:**