Chapter 5.1, Problem 5.12E

(a)

To determine

To explain why it would be difficult for managers to inspect the last twenty iPhones that were produced today.

Explanation of Solution

 An SRS of only twenty iPhones is such a small sample size in relation to how large the population size is and may not provide a good indication as to the quality of the phones.

(b)

To determine

To explain that the idea mentioned in the question isn’t good.

Explanation of Solution

It isn’t good because the last twentyiPhones produced may all be defective, and would not provide an accurate representation.

(c)

To determine

To explain why this sampling method is not an SRS.

Explanation of Solution

 An SRS would ensure that every phone has an equal chance of being selected for inspection. However, by selecting every fiftieth phone, not every phone would have an equal chance to be selected.