Question

An discrete random variable 'X' has value $x=k^2$ where k is an integer ranging from $1\le k\le 4$. Then the expected value of $E\left[x\right]$ is equal to (Assuming probabilities $P_k=0.4,0.25,0.15,0.1$)

• A. 10
• B. 1.28
• C. 3.25
• D. 4.35

Answer 1

The correct option is D 4.35

$E\left[X\right]=\sum _{k=-\infty }^{\infty }{x}_k{P}_k\left(x_k\right)$

$=1\times 0.4+4\times 0.25+9\times 0.15+16\times 0.1$

$=4.35$