Concept explainers
Applying the Concepts 10–2
Stopping Distances Revisited
In a study on speed and braking distance, researchers looked for a method to estimate how fast a person was traveling before an accident by measuring the length of the skid marks. An area that was focused on in the study was the distance required to completely stop a vehicle at various speeds. Use the following table to answer the questions.
MPH | Braking distance (feet) |
20 | 20 |
30 | 45 |
40 | 81 |
50 | 133 |
60 | 205 |
80 | 411 |
Assume MPH is going to be used to predict stopping distance.
Find the linear regression equation.
What does the slope tell you about MPH and the braking distance? How about the y′ intercept?
Find the braking distance when MPH = 45.
Find the braking distance when MPH = 100.
Comment on predicting beyond the given data values.
See page 604 for the answers.
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Elementary Statistics: A Step By Step Approach
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