Answer to Question #54997 in Physics for Lia

Question

If the average American driver goes 5000 mi each year on interstate highways, how much less time did the average driver spend on interstate highways each year as a result of the 1995 increase in the speed limit from 55 mi/h to 65 mi/h?

Answer 1

1. Let's find how much time average American driver used to spend on interstate before 1995:

t = 5000 / 55 = 90.9 hours

2. And the same after 1995:

t = 5000 / 65 = 76.9 hours

3. And finally, the difference between time spent:

dt = 90.9 - 76.9 = 14 hours

So average American driver spends each year 14 hours less then he had spent before 1995.