Dottie’s Tax Service specializes in federal tax returns for professional clients, such as physicians, dentists, accountants, and lawyers. A recent audit by the IRS of the returns she prepared indicated that an error was made on 7% of the returns she prepared last year.

Assuming this rate continues into this year and she prepares 80 returns, what is the probability that she makes errors on:

a. More than six returns?

b. At least six returns?

c. Exactly six returns?