find the probability that the number x of correct answer is more than 2

Question

assume that random guesses are made for five multiple-choice question on an ACT test, so that there are n=5 trials. each with probability of success (correct) given by p=0.20. use the binomial probability table to find the indicated probability for the number of correct answers.

Answer 1

P(3 correct) = ₅C₃•0.2³•0.8²

P(4 correct) = ₅C₄•0.2⁴•0.8

P(5 correct) = ₅C₅•0.2⁵

 

Simplify and add if question is 'what is probability of at least 3 correct?' Or use your table, appropriately.