Question

Probability that a man can hit the target is 3/4. He tries 5 times . Find the probability that he hits the target at least 4 times .

A) 81/256 B) 81/128 C) 24/32 D) 15/43

Answer 1

It is a question of binomial theorem , here n = 5 and p = 3/4 and q = 1- p = 1/4
So hitting the target atleast four times means , it is hit 4 or five times.
So P(x $\ge$4) = ⁵C₄ ( 3/4)⁴(1/4)¹ + ⁵C₅ ( 3/4)⁵(1/4)⁰ = 81/128