Question

Find the value of P(X=3) if X is the discrete random variable taking values x1, x2, x3 where P(X=0)=0, P(X=1) = 1/4 and P(X=2) = 1/4

(a) 1

(b) 1/2

(c) 1/3

(d) 1/4

I have been asked this question by my college director while I was bunking the class.

The question is from Random Variables and its Probability Distributions topic in portion Probability of Mathematics – Class 12

Answer 1

Right choice is (b) 1/2

To explain I would say: We know that ∑P(xi) = 1

P(X) = P(X=0) + P(X=1) + P(X=2) + P(X=3)

1 = 1/4 + 1/4 + P(X=3)

P(X=3) = \(\frac {1}{2}\)