Refer back to given Exercise about stopping distance and vehicle speed. The least squares line for these data is
Average Distance = -44.2 + 5.7 (Speed)
a. Use this equation to estimate the average stopping distance when the speed is 80 miles per hour. Do you think this is an accurate estimate? Explain.
b. Draw a scatterplot of the data, as instructed in Exercise 3.7(b). Use the scatterplot to estimate the average stopping distance for a speed of 80 mph.
c. Do you think the data on stopping distance and vehicle speed shown in Exercise 3.7 describe the relationship between these two variables for all situations? What are some other variables that should be considered when the relationship between stopping distance and vehicle speed is analyzed?
Exercise
The following table shows the relationship between the speed of a car (mph) and the average stopping distance (feet) after the brakes are applied:
|
Speed (mph)
|
0
|
10
|
20
|
30
|
40
|
50
|
60
|
70
|
|
Distance (ft)
|
0
|
20
|
50
|
95
|
150
|
220
|
300
|
400
|
a. In the relationship between these two variables, which is the response variable (y) and which is the explanatory variable (x)?
b. Draw a scatterplot of the data. Characterize the relationship between stopping distance and speed.