An auditor for the Internal Revenue Service is selecting a sample of 6 tax returns for an audit. If 2 or more of these returns are "improper," the entire population of 100 tax returns will be audited. What is the probability that the entire population will be audited if the true number of improper returns in the population is
a. 25?
b. 30?
c. 5?
d. 10?
e. Discuss the differences in your results, depending on the true number of improper returns in the population.