Chapter 13, Problem 25E

Conclusions A catalog sales company promises to deliver orders placed on the Internet within 3 days. Follow-up calls to a few randomly selected customers show that a 95% confidence interval for the proportion of all orders that arrive on time is 88% ± 6%. What does this mean? Are these conclusions correct? Explain.

1. a) Between 82% and 94% of all orders arrive on time.
2. b) Ninety-five percent of all random samples of customers will show that 88% of orders arrive on time.
3. c) Ninety-five percent of all random samples of customers will show that 82% to 94% of orders arrive on time.
4. d) We are 95% sure that between 82% and 94% of the orders placed by the sampled customers arrived on time.
5. e) On 95% of the days, between 82% and 94% of the orders will arrive on time.