Car Math Question?

Question

A car is traveling at a constant speed. After 2.5 hours, the car has traveled 80 miles. If the car continues to travel at the same constant speed, how many hours will it take to travel 270 miles?

Answer 1

For motion at constant speed, there is a direct relationship between distance (d), speed (v), and time (t):

 

d = vt

 

The information in the first sentence allows us to calculate the constant speed v, since it gives us distance traveled over a certain time.  Specifically:

 

80 miles = v*(2.5 hours) --> v = 80 miles/2.5 hours --> v = 32 miles/hour.

 

In the last sentence, we are given a new distance d' = 270 miles, and are asked to calculate t', the new time in hours, now knowing that v = 32 miles/hour.  This just involves using the first equation above again, and solving for t' knowing d' and v.

 

Hope this helps, Nancy!