Question

Let X be a discrete random variable. The probability distribution of X is given below:

X	30	10	–10
P(X)	`1/5`	`3/10`	`1/2`

Then E(X) will be:

Options

• 1

• 4

• 2

• 30

Answer 1

4

Explanation:

E(X) = ΣX · P(X)

= `30 xx 1/5 + 10 xx 3/10 - 10 xx 1/2`

= 6 + 3 – 5

= 4