Most binomial probability calculations required in these exercises can be done by using Table C or the Normal approximation. Your instructor may request that you use the binomial probability formula or software. In exercises requiring the Normal approximation, you should use the continuity correction if you studied that topic.

Question 5.24

5.24 Paying for music downloads.

A survey of Canadian teens aged 12 to 17 years reported that roughly 75% of them used a fee-based website to download music.7 You decide to interview a random sample of 15 U.S. teenagers. For now, assume that they behave similarly to the Canadian teenagers.

  1. What is the distribution of the number who used a fee-based website to download music? Explain your answer.
  2. What is the probability that at least 12 of the 15 teenagers in your sample used a fee-based website to download music?