Consider each situation described below. Identify the population and the sample, explain what the parameter p or μ represents, and tell whether the methods of this chapter can be used to create a confidence interval. If so, find the interval.
(a) The service department at a new car dealer checks for small dents in cars brought in for scheduled maintenance. It finds that 22 of 87 cars have a dent that can be removed easily. The service department wants to estimate the percentage of all cars with these easily repaired dents.
(b) A survey of customers at a supermarket asks whether they found shopping at this market more pleasing than at a nearby store. Of the 2,500 forms distributed to customers, 325 were filled in and 250 of these said that the experience was more pleasing.
(c) A poll asks visitors to a Web site for the number of hours spent Web surfing daily. The poll gets 223 responses one day. The average response is three hours per day with s = 1.5.
(d) A sample of 1,000 customers given loans during the past two years contains 2 who have defaulted.