chapter 5 non regen 1 We expect a cars highway gas mileage t

chapter 5 non regen

1. We expect a car\'s highway gas mileage to be related to its city gas mileage. Data for all 1198 vehicles in the government\'s 2008 Fuel Economy Guide gives the following regression line: highway mpg = 4.62 + (1.109 X city mpg) for predicting highway mileage from city mileage.

What is the slope of this line? Give your answer to 3 decimal places.

Say in words what the numerical value of the slope tells us.

A. On the average, highway mileage increases by 4.62 mpg for each additional mpg in city mileage.

B. On the average, highway mileage increases by 1.109 mpg for each additional mpg in city mileage.

C. On the average, highway mileage decreases by 1.109 mpg for each additional mpg in city mileage.

What is the intercept? Give your answer in mpg\'s to 2 decimal places.

Explain why the value of the intercept is not statistically meaningful.

A. Because this is the highway mileage for zero city mpg.

B. Because this is the highway mileage for slope 0.

C. Because this is an average value, calculated from a sample.

Find the predicted highway mileage for a car that gets 16 miles per gallon in the city. Give your answer in mpg to 2 decimal places.  

= __________?

Find the predicted highway mileage for a car that gets 28 miles per gallon in the city. Give your answer in mpg to 2 decimal places.  

= ____________?

A. Pink

B. Blue

C. Yellow

2. You use the same bar of soap to shower each morning. The bar weighs 80 grams when it is new. Its weight goes down by 6 grams per day on the average.

What is the equation of the regression line for predicting weight from days of use?

A. Weight = 80 - 6 ? days

B. days = 80 - 6 ? weight

C. Weight = 6 + 80 ? days

D. Weight = 80 + 6 ? days

Box 1: Select the best answer

Match your answers below.

A. 31.3333

B. 1.3784

C. 0.9623

D. 16.1328

E. 3.5

Use these basic measures to find the equation of the least-squares line for predicting y from x.

Box 1: In each pull-down on the left, select the letter (a, b, c, etc.) of the matching answer in the right-hand column

Box 2: Select the best answer

8. A researcher obtained the average SAT scores of all students in each of the 50 states, and the average teacher salaries in each of the 50 states. She found a negative correlation between these variables. The researcher concluded that a lurking variable must be present. By lurking variable she means

A. a variable that is not among the variables studied but which affects the response variable.

B. any variable that produces a large residual.

C. the true variable, which is explained by the explanatory variable.

D. the true cause of a response.

Box 1: Select the best answer

Solution

the slope of this line = 1.109

B. On the average, highway mileage increases by 1.109 mpg for each additional mpg in city mileage.

Intercept = 4.62

A. Because this is the highway mileage for zero city mpg.

the predicted highway mileage for a car that gets 16 miles per gallon in the city.=22.36

the predicted highway mileage for a car that gets 28 miles per gallon in the city.=35.672

A. Pink

A. Weight = 80 - 6