¶ 2013 AMC8 Problem 7
Problem:
Trey and his mom stopped at a railroad crossing to let a train pass. As the train began to pass, Trey counted cars in the first seconds. It took the train minutes and seconds to clear the crossing at a constant speed. Which of the following was the most likely number of cars in the train?
Answer Choices:
A.
B.
C.
D.
E.
Solution:
Because Trey counted cars in seconds, close to cars passed in seconds or minute. In minutes seconds, about cars passed, so there were approximately cars in the train.
Two minutes and seconds is seconds. Let be the number of cars, and set up a proportion:
Solving gives , so . Approximately train cars passed.
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions