One of the biggest frustrations for the consumer electronics industry is that customers are accustomed to returning goods for any reason (C. Lawton, "The War on Returns," The Wall Street Journal, May 8, 2008, pp. D1, D6). Recently, it was reported that returns for "no trouble found" were 68% of all the returns. Consider a sample of 20 customers who returned consumer electronics purchases. Use the binomial model to answer the following questions:
a. What is the expected value, or mean, of the binomial distribution?
b. What is the standard deviation of the binomial distribution?
c. What is the probability that 15 of the 20 customers made a return for "no trouble found"?
d. What is the probability that no more than 10 of the customers made a return for "no trouble found"?
e. What is the probability that 10 or more of the customers made a return for "no trouble found"?