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
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).