FRM一级易错题精选:Use the following joint probability

Use the following joint probability distribution to answer the questions below.

 
  Y=1 Y=2 Y=3
X=1  
0.05
 
0.05
 
0.10
X=2  
0.05
 
0.10
 
0.15
X=3  
0.15
 
0.15
 
0.20

The expected value of Y is closestto:  
 A. 0.2.

B. 1.0.
 
C. 2.2.
 
D. 2.3.

Answer: 

12.C
 
p(Y=1)=0.05+0.05+0.15=0.25, p(Y=2)=0.05+0.10+0.15=0.30, and p(Y=3)=0.10+0.15+0.20=0.45, so E(Y)=0.25(1)+0.30(2)+0.45(3)=2.20.