A truck enters a highway driving

Question

A truck enters a highway driving 60 mph. A car enters the highway at the same place 7 minutes later and drives 68 mph in the same direction. From the time the car enters the highway, how long will it take the car to pass the truck?

Answer 1

d = rt, and the distances are equal. 7 minutes is 7/60 hr.

 

60(t + 7/60) = 68t

60t + 7 = 68t

8t = 7

t = 7/8 hr 

 

(7/8)60 = 52.5 mins = 52 mins, 30 secs