Question

A Stats test has 5 multiple choice questions with four choices with one correct answer each. If we just randomly guess on each of the 5 questions, what is the probability that you get exactly 2 questions correct

Answer 1

0.0512

Explanation:

Probability of making a correct guess ; p = 1 / 5 = 0.2

q = 1 - p = 1 - 0.2 = 0.8

Number of questions, n = 5

Using the binomial probability relation :

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

P(x = 3) = 5C3 * 0.2^3 * 0.8^2

P(x = 3) = 0.0512