Based on past experience, 20% of the contacts made by a firm's sales representatives result in a sale being made. Charlie has contacted 100 potential customers but has made only 10 sales. Assume that Charlie's contacts represent a simple random sample of those who could have been called upon. Given this information:
a. What is the sample proportion, proportion of contacts that resulted in a sale being made?
b. For simple random samples of this size, what is the probability that p ≤ 0.10?
c. Based on your answer to (b), would you tend to accept Charlie's explanation that he "just had a bad day"?