The following table reports the U.S. credit/debit card industry's market share data for 2015. A random sample of 100 credit/debit card users is to be questioned regarding their satisfaction with their card company. For simplification, assume that each card user carries just one card and that the market share percentages are the percentages of all card customers that carry each brand.

 

Credit debit Card Market Share % Visa 59 26 MasterCard Discover American Express 13 Source: Based on Nilson Report data, June 2015. a. For random samples of l100 card users, what is the expected number of customers who carry Visa? Discover? b. Please use a normal approximation to find the probability that half or more of the sample of card users carry Visa? American Express? c. Justify the use of the normal approximation to the binomial in answering the question in part c.