Professional tennis. Serena Williams made a successful first serve 67% of the time in a Wimbledon finals match against her sister Venus. If she continues to serve at the same rate the next time they play and serves 6 times in the first game, determine the following probabilities. (Assume that each serve is independent of the others.)

a) All 6 first serves will be in.

b) Exactly 4 first serves will be in.

c) At least 4 first serves will be in.