Question

Suppose that 70% of all voters prefer Candidate A. If 4 people are chosen at random for a poll, what is the probability that exactly 1 of them favor Candidate A?

Answer 1

0.0756

Explanation:

p(success), p = 70% = 0.7

Nunber of trials, n = 4

q = 1 - p = 1 - 0. 7 = 0.3

x = 1

The question meets the requirements of a binomial probability distribution :

P(x = x) = nCx * p^x * q^(n-x)

P(x = 1) = 4C1 * 0.7^1 * 0.3^(4-1)

P(x = 1) = 4C1 * 0.7 * 0.3^3

P(x = 1) = 4 * 0.7 * 0.027

P(x = 1) = 0.0756