Chapter 5, Problem 6CT

In Exercises 5 and 6. determine whether you can use a normal distribution to approximate the binomial distribution. If you can, use the normal distribution to approximate the indicated probabilities and sketch their graphs. If you cannot, explain why and use a binomial distribution to find the indicated probabilities.

6. A survey of U.S. adults found that 86% of those who use the Internet keep track of their online passwords in their heads. You randomly select 30 U.S. adults who use the Internet. Find the probability that the number who keep track of their online passwords in their heads is (a) exactly 25, (b) more than 25. and (c) less than 25. Identify any unusual events. Explain. (Source: Pew Research Center)