The time that it takes to get to campus varies inversely as your driving rate.

Question

The time that it takes to get to campus varies inversely as your driving rate. Averaging 15 miles per hour in terrible traffic, it takes you 2.25 hours to get to campus. How long would the trip take averaging 45 miles per hour?

Answer 1

We are given the average speed (15 mi/h) and the time it takes to get to campus using that speed (2.25 h). Since time is inversely related to speed (v=d/t) we can plug in the values to find the distance to campus.

 

15 mi/h = x / 2.25 h

x=33.75 mi

 

Now that we know the distance, we can plug it in along with the new speed (45 mi/h) to find the new time.

45 mi/h = 33.75 mi / x

x=33.75 / 45 mi h

x = 0.75 h