5.14 Coupons Driving Visits:  A store randomly samples 603 shoppers over the course of a year and finds that 142 of them made their visit because of a coupon they'd received in the mail. Construct a 95% confidence interval for the fraction of all shoppers during the year whose visit was because of a coupon they'd received in the mail.
(please round all proportions to four decimal places)


a) Estimate the true proportion of shoppers during the year whose visit was because of a coupon they'd received in the mail.
( , )


b) Interpret the confidence interval in context.