There are two motorcyclists on a single lane road. They are 25 miles apart. At a
ID: 2095208 • Letter: T
Question
There are two motorcyclists on a single lane road. They are 25 miles apart. At a signla, they start moving toward each other with constant speeds. The first motorcyclist rides at 20 mph; the second rides at 30 mphs. When the signal goes off, a fly on the helmet of the first motorcyclist is startled and starts flying toward the second motorcyclist at 40 mph. When the fly reaches the second motorcyclist (now moving toward the firt), he immediately reverses course and flies back to the first motorcyclist. Then the fly gets back to the first motorcyclist, he reverses course again. The fly continues to fly backwards and fowards between the two motorcyclists until they all collide. How many maniles will the fly have traveled before his life is extinguished?
Explanation / Answer
The two motorcyclist are moving at 20+30 mph towards each other. They are 25 miles apart. For the two motorcyclist to collide, it would take 25/50 = 0.5 hrs. Note that when the two motorcyclist collide, the fly collides with them as well. Therefore, the fly is in motion for the same amount time it took the two motorcyclists to collide: 0.5hrs. Travelling at 40mph, the fly has flown a total of 40*0.5 = 20 miles.