When will they lose contact?

Question

A truck and a car leave a service station at the same time and travel in the  same direction. The truck travels at 60 mph and the at 54 mph. they can maintain radio conact within range of 12 miles. When will they lose contact?

 

 

They will loose contact after __ hours. 

Answer 1

The truck is driving 6mph faster than the car and will travel 6 miles ahead of the car after the first hour of driving.  After the second hour, and both vehicles are continuing their speed without stopping, the truck will have travelled an additional 6 miles ahead of the car.  The total miles that the truck travelled ahead of the car (2 hours x 6 miles) is 12 miles.  12 miles is the maximum range of radio contact between the two vehicles.  Therefore, the two vehicles will loose contact with each other two hours after they began driving from the service station.