Question

If X assumes value of $5,1$ and $2$ with the probability of $0.1,0.5$ and $0.4$ respectively. What the expected value of X?

• A. $1.20$
• B. $3.15$
• C. $1.80$
• D. $1.25$

Answer 1

The correct option is C $1.80$

According to the question, the probability distribution of variable X can be written as:

X	1	2	5
P(X)	0.5	0.4	0.1

The expected value of X is nothing but the mean of X, i.e., $\mu$

Hence, $\mu =E\left(X\right)={\sum }_{i=1}^n{x}_i{p}_i$

$\mu =1\times 0.5+2\times 0.4+5\times 0.1=0.5+0.8+0.5=1.80$