Approximating Binomial Probabilities In Exercises 19-21, 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. Identify any unusual events. Explain.
Fraudulent Credit Card Charges A survey of U.S. adults found that 41% have encountered fraudulent charges on their credit cards. You randomly select 100 U.S. adults. Find the probability that the number who have encountered fraudulent charges on their credit cards is (a) exactly 40, (b) at least 40, and (c) fewer than 40.
Screen Lock A survey of U.S. adults found that 28% of those who own smartphones do not use a screen lock or other security features to access their phone. You randomly select 150 U.S. adults who own smartphones. Find the probability that the number who do not use a screen lock or other security features to access their phone is (a) at most 40, (b) more than 50, and (c) between 20 and 30, inclusive.