A catalog sales company promises to deliver orders placed on

A catalog sales company promises to deliver orders placed on the Internet within fourfour days. Follow-up calls to randomly selected customers show that a 9595% confidence interval for the proportion of all orders that arrive on time is 8686%plus or minus±66%. What does this mean? Are the following conclusions correct?

(a) Between 8080% and 9292% of all orders arrive on time.

(b) 9595% of all random samples of customers show that 8686% of orders arrived on time.

(c) 9595% of all random samples of customers will show that 8080% to 9292% of orders arrived on time.

(d) We are 9595% sure that between 8080% and 9292% of the orders placed by the customers in this sample arrived on time.

(e) On a randomly chosen day, we can be 9595% confident that between 8080% and 9292% of the large volume of orders will arrive on time.

What does this mean?

A. This means the procedure that produced this interval generates ranges that hold the population mean for 9595% of samples.

B. This means that we are 9595% sure that all orders arrive on time.

C. This means that there is a 9595% chance that the mean proportion is 8686%.

D. This means that there is a 9595% chance that the standard deviation is 66%.

Are the conclusions given in the problem statement correct? Select all that apply.

(a)

(b)

(c)

(d)

(e)

None of the above

Solution

What does this mean? Are the following conclusions correct?

(d) We are 95% sure that between 80% and 92% of the orders placed by the customers in this sample arrived on time.

A. This means the procedure that produced this interval generates ranges that hold the population mean for 9595% of samples.