If a binomial distribution applies with a sample size of n = 20, find

a. the probability of 5 successes if the probability of a success is 0.40

b. the probability of at least 7 successes if the probability of a success is 0.25

c. the expected value, n = 20, p = 0.20

d. the standard deviation, n = 20, p = 0.20