Applied Mathematics for Electrical Engineering (3130908)

BE | Semester-3   Winter-2019 | 26-11-2019

Q3) (c ( ii ))

The joint probability density function of two random variables x and y is given by f(x,y) = k(x+2y)   ;0<x<1 , 0<y<20               ;elsewhere. Find the marginal density function of x and y.

The marginal probability density function of X is
 
Fxx = 02f(x,y) dy
 
Fxx = 02k ( x+2y ) dy
 
Fxx = k  xy+ 2y2 2 02
 
Fxx = k [  2x+4  - 0 ]
 
Fxx = k  2x+4  ; 0<x<1.
 
The marginal probability density function of Y is
 
FYy = 01f(x,y) dx
 
Fxx = 01k ( x+2y ) dx
 
Fxx = k  x22+2xy 01
 
Fxx = k [ ( 122+2y(1) ) - 0 ]
 
Fxx = k  12+2y  ; 0<y<2.