Chapter 19, Problem 5E

(a)

To determine

To explain what does this mean and are the conclusions correct or not.

Answer to Problem 5E

It is incorrect.

Explanation of Solution

It is given in the question that a catalogue sales company promises to deliver orders on the internet within three days. Thus, the conclusion is given on the confidence interval calculated of the proportion of orders as: between $\text{84\% and 94\%}$ of all orders arrive on time. This is simply incorrect as from the given information in the question.

(b)

To determine

To explain what does this mean and are the conclusions correct or not.

Answer to Problem 5E

It is incorrect.

Explanation of Solution

It is given in the question that a catalogue sales company promises to deliver orders on the internet within three days. Thus, the conclusion is given on the confidence interval calculated of the proportion of orders as: $\text{95\%}$ of all random samples of customers will show that $\text{88\%}$ of orders arrive on time. This conclusion is incorrect because different samples will give different results ad many fewer than $\text{95\%}$ will have $\text{88\%}$ on time.

(c)

To determine

To explain what does this mean and are the conclusions correct or not.

Answer to Problem 5E

It is incorrect.

Explanation of Solution

It is given in the question that a catalogue sales company promises to deliver orders on the internet within three days. Thus, the conclusion is given on the confidence interval calculated of the proportion of orders as: $\text{95\%}$ of all random samples of customers will show that $\text{82\% to 94\%}$ of orders are on time. This conclusion is incorrect as the interval is about the population proportion, not the sample proportion in different samples.

(d)

To determine

To explain what does this mean and are the conclusions correct or not.

Answer to Problem 5E

It is incorrect.

Explanation of Solution

It is given in the question that a catalogue sales company promises to deliver orders on the internet within three days. Thus, the conclusion is given on the confidence interval calculated of the proportion of orders as: we are $\text{95\%}$ sure that between $\text{82\% to 94\%}$ of the orders placed by the sampled customers arrived on time. This statement is incorrect because in this ample we know $\text{88\%}$ arrived on time.

(e)

To determine

To explain what does this mean and are the conclusions correct or not.

Answer to Problem 5E

It is incorrect.

Explanation of Solution

It is given in the question that a catalogue sales company promises to deliver orders on the internet within three days. Thus, the conclusion is given on the confidence interval calculated of the proportion of orders as: On $\text{95\%}$ of the days between $\text{82\% to 94\%}$ of the orders will arrive on time. This conclusion is incorrect because the interval is about the parameter, not about the days.