Question

The p.m.f. of a random variable X is

P(x) = `(5 - x)/10`,   x = 1, 2, 3, 4
       = 0,            otherwise

The value of E(X) is ______ 

विकल्प

• 0

• 1

• 2

• 3

Answer 1

The p.m.f. of a random variable X is

P(x) = `(5 - x)/10`,   x = 1, 2, 3, 4
       = 0,            otherwise

The value of E(X) is 2.

Explanation:

The p.m.f. of the r.v. X is as follows:

X = x	1	2	3	4
P(X = x)	`2/5`	`3/10`	`1/5`	`1/10`

∴ E(X) = ∑x_i.P(x_i)

= `1(2/5) + 2(3/10) + 3(1/5) + 4(1/10)`

= 2