Problem:
The traffic on a certain east-west highway moves at a constant speed of miles per hour in both directions. An eastbound driver passes westbound vehicles in a five-minute interval. Assume vehicles in the westbound lane are equally spaced. Which of the following is closest to the number of westbound vehicles present in a -mile section of highway?
Answer Choices:
A.
B.
C.
D.
E.
Solution:
Since the vehicles moving in each direction are traveling at miles per hour, the eastbound traffic is actually traveling at miles per hour relative to the westbound traffic. Thus, in five minutes the eastbound driver will actually count the number of westbound vehicles in a ten-mile section of highway. Since vehicles are in a ten-mile section, there will be vehicles in a 100 -mile section of highway.