The highway patrol uses the following formula to estimate the speed (s), in miles per hour, at which a car was traveling if the car skidded d feet before stopping after the brakes were applied:
The variable f relates to the friction of the road surface. The following table estimates ffor certain types of road surfaces and conditions.
If a car skids 80 feet on wet gravel, what is the approximate speed, in miles per hour, at which the car was traveling?
A . 43.8
B . 31.4
C . 22.6
D . 15.5
E . 10.4
Answer: D