The IRS reports that 15% of the tax returns where the adjusted gross income exceeded $1 million will be subject to computer audit. For a particular year, a CPA completed 16 returns where the adjusted gross income exceeds $1 million.

a.) Which probability model does this situation follow?

b.) What is the probability that exactly one of these returns is audited?

I realize that A is just asking me for a probability formula that I will use to solve for in B. But I don't get how I can solve B if I don't have the total number of audits completed.

Please help me! I would greatly appreciate it!