Gas Mileage Again in the Data Desk Lab Last Week $= 60.9 \% \quad$

question 762

Essay

Gas mileage again In the Data Desk lab last week you analyzed the association between a
car's fuel economy and its weight. Another important factor in the amount of gasoline a car
uses is the size of the engine. Called "displacement", engine size measures the volume of
the cylinders in cubic inches. The regression analysis is shown. Dependent variable is:
MPG
89 total cases of which 0 are missing
R squared $= 60.9 \% \quad$ R squared (adjusted) $= 60.0 \%$
$s = 3.056$ with $89 - 2 = 87$ degrees of freedom


$\begin{array}{llrrr}\text { Source } & \text { Sum of Squares } & \text { df } & \text { Mean Square } & \text { F-ratio } \\\text { Regression } & 696.744 & 1 & 696.744 & 74.6 \\\text { Residual } & 448.236 & 48 & 9.33826 &\end{array}$

$\begin{array}{lllll}\text { Variable } & \text { Coefficient } & \text { s.e. of Coeff } & \text { t-ratio } & \text { prob } \\\text { Constant } & 34.9799 & 1.231 & 28.4 & \text { Ş } 0.0001 \\\text { Eng. Displemt } & -0.066196 & 0.0077 & -8.64 & \text { S } 0.0001\end{array}$



a. How many cars were included in this analysis?
b. What is the correlation between engine size and fuel economy?
c. A car you are thinking of buying is available with two different size engines, 190 cubic
inches or 240 cubic inches. How much difference might this make in your gas mileage?
(Show work)

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Definitions:

Marginal-Utility Schedules

Charts or tables showing the relationship between the quantity of a good consumed and the marginal utility or satisfaction received from consuming each additional unit.

Maximum Utility

The highest level of satisfaction or benefit that a consumer can obtain from consuming goods and services, given their income and prices of goods.

Satisfaction Per Dollar

A measure of the utility or happiness a consumer gains per unit of expenditure.

MUₐ /Pₐ

The ratio of marginal utility (MUₐ) to the price (Pₐ) of an item, often used in consumer choice theory to evaluate optimal consumption.