A survey of your customers shows, to your surprise, that 42 out of 200 randomly selected customers were not satisfied with after-sale support and service.
a. Find the summary statistics: the sample size, n; the sample percentage, p; and the standard error, Sp.
b. Find the two-sided 95% confidence interval for the percent dissatisfied among all of your customers (i.e., not just those surveyed).
c. Your population consists of 28,209 customers. Convert the percentages representing the endpoints of the confidence interval in part b to numbers of people in the population. State and interpret your result as a confidence interval for the population number of dissatisfied customers.