Chapter 10, Problem 9E

(a)

To determine

To Explain: the model appears to be better than the linear model.

Explanation of Solution

Given:

  

  

By observing the figure, that it is not displaying any pattern. That is the model fitted to data is more suitable. Therefore, this is a sign that this model looks to better than the linear model.

(b)

To determine

To write: an equation on this model using the regression analysis.

Explanation of Solution

Given:

  

  

The slope of the regression line equal to 1.17791 and intercept is equals to 0.624932. Therefore the equation of model is

  $\frac{gal}{100}=0.625+1.178\times weight$

(c)

To determine

To Explain: the slope of this line.

Explanation of Solution

Given:

  

  

There is slope is of 1.178. it implies that for each 1000 pounds in weights of car model expects that the fuel consumption of the car is increasing by 1.178 gal per 100 miles.

(d)

To determine

To find: the number of miles per gallon expects a 3500-pound car to get.

Answer to Problem 9E

21.06 miles/gal expected from a 3500 pound car.

Explanation of Solution

Given:

  

  

Calculation:

Estimated fuel consumption of 3500 pound is

  $\begin{array}{c}\frac{gal}{100}=0.625+1.178\times weight\\ \frac{gal}{100}=0.625+1.178\times \left(3.5\right)\\ =0.625+4.123\\ =4.748\end{array}$

Therefore, model expects that a 3500 pounds car weight needs 4.745 gal to drive 100 miles that is 0.04748 gal to drive one mile so

1/0.04748 miles/gal =21.06 miles/gal

So 21.06 miles/gal expected from a 3500 pound car.