A representative from a national soft drink manufacturer is responsible for conducting street interviews with randomly selected persons in a given major market. Historically, about 2 in 10 people have a preference for their principle product. How many people can he expect to approach, with 90% confidence, before he finds one that prefers their principle product?
What is the probability that the representative (in problem above) will find 2 persons who prefer their principle product out of the first 5 approached?