Suppose X and Y Are Random Variables Whose Density Function

Multiple Choice

Suppose X and Y are random variables whose density function is given by $f ( x , y ) = \left\{ \begin{array} { c l } 0.2 e ^ { - ( 05 x + 0.4 y ) } & \text { if } x \geq 0 , y \geq 0 \\0 & \text { otherwise }\end{array} \right.$ is a joint density function.

A) 0.2
B) $\frac { 1 } { e }$
C) 0.25
D) 1
E) $\frac { 1 } { 2 e }$
F) $\frac { 1 } { \sqrt { e } }$
G) 0.1
H) 0