Chapter 12, Problem 30E

(a)

To determine

To explain what statistics have you calculated.

Answer to Problem 30E

Average is used.

Explanation of Solution

It is given that when you fill your gas, you figured out how many miles per gallon your car got. So, the results were written down as after the six fill ups in the past few months. Thus, it appears the car gets $28.8$ miles per gallon. Thus, we have calculated in the question that average gas mileage for the last six fill-ups. As the past few results are summoned up so we have used the average result.

(b)

To determine

To find out what is the parameter you are trying to estimate.

Answer to Problem 30E

We are trying to estimate the mean.

Explanation of Solution

It is given that when you fill your gas, you figured out how many miles per gallon your car got. So, the results were written down as after the six fill ups in the past few months. Thus, it appears the car gets $28.8$ miles per gallon. Thus, the parameter we are trying to estimate is mean gas mileage for the vehicle as from it we can finally get the average result for the mileage of the car.

(c)

To determine

To explain how might be your result be bias.

Explanation of Solution

It is given that when you fill your gas, you figured out how many miles per gallon your car got. So, the results were written down as after the six fill ups in the past few months. Thus, it appears the car gets $28.8$ miles per gallon. Thus, the result might be biased because conditions of late may not be typical in this study conducted.

(d)

To determine

To explain what parameter is it trying to estimate.

Answer to Problem 30E

Mean gas mileage for all cars of this model is trying to be estimated.

Explanation of Solution

It is given that when you fill your gas, you figured out how many miles per gallon your car got. So, the results were written down as after the six fill ups in the past few months. Thus, it appears the car gets $28.8$ miles per gallon. Thus, the parameter it is trying to estimate is the mean gas mileage for all cars of this model.