The time t is required a certain distance varies inversely with the speed r if it takes 4 hours to drive the distance at 40 miles per hour how long will it take to drive the same distance at 55 miles per hour.

A. about 2.91 hours

B. 160 hours

C. about 22 hours

D. about 5.50 hours

Is the answer A?

We have to determine first the distance. Given the speed of 40 miles/hour and time of 4 hours, distance can be solved from the formula, speed = distance / time. Let’s evaluate:

Distance = speed x time

Distance = 40 x 4 = 160 miles.

At same distance, we have to determine time it will take at the speed of 40 miles/hour. Therefore we have:

speed = distance / time

time = distance / speed

time = 160 / 55 = 2.91 hours

You are correct, the answer is A