What is the probability a student answer at least 4 out of five questions correctly on a quiz? n=15, x>=4, p=.20, q=.80

Answer 1

Find P(4) and P(5). Add both together for your probability.

You can use a binomial probability table, which is easier, or do this by hand using the following formula:

P(x) = (nCx)(p^x)[q^(n-x)]

Use the values given in your problem to calculate P(4) and P(5).