I need help with this problem...



A sale representative makes a sale at approximately one-third of the offices she calls on. If, on a given day, she goes to four offices, what are the probabilities that she will make a sale at (a) all four offices? (b) none of the offices, and (c) at least one office?

I'll help you with the first problem. If the probability of success on any one office visit is 1/3, then the probability of being successful 4 times in a row is (1/3)*(1/3*(1/3)*(1/3).

As for the second, recall that the probability of not being successful on any patricular office visit is 1 - P(success) = 1 - 1/3.