A quiz has 20 multiple choice questions, each with a choice of 4 answers. If Jay guesses an answer for each question at random, find the probability that he will score 75% on this quiz, correct to 2 significant figures.

Question

Answer: 0.000 003 4
Thanks for any help

Answer 1

this is a binomial probability
... p(correct) = .25
... p(wrong) = .75

(c + w)^20

p(75% correct) = 20C5 * .25^15 * .75^5