Question

A motorcycle travels north along

road at constant speed of 45 mph. At
2pm, a truck is 348 miles away
driving south along the same road
at constant speed. They pass each other
at 6pm. What is the speed of the
truck ?

Answer 1

42 mph

Explanation:

From 2 p.m. to 6 p.m. 4 hours passed, so the truck and the motorcycle were on the road for 4 hours until they met.

Motorcycle in 4 hours at a constant speed of 45 mph travelled

`45\cdot 4=180\ miles`

The distance between the motorcycle and the truck is 348 miles, so the truck travelled

`348 -180=168\ miles`

If x mph is truck's speed, then

`168=4\cdot x\\ \\x=(168)/(4)=42\ mph`