barakhaiev wrote:

A train traveling at a constant speed down a straight track crosses a certain line on the track. If the rear wheels of the train cross the line 2 seconds after the front wheels, and the centers of the rear and front wheels are 100 feet apart, which of the following expresses the speed of the train in miles per hour?

1 mile = 5280 feet

(A) \((100/5280)(60^2/2)\)

(B) \((100/5280)(60/2)\)

(C) \((100/5280)(2/60^2)\)

(D) \((100/60^2)(5280/2)\)

(E) \((100/60)(5280/2)\)

Speed of the train would be 100/2 feet per second, as it covers the distance of 100 feet in 2 seconds.

We should transform this to miles per hour:

100 feet=100/5280 miles;

2 seconds=2/60^2 hours;

Hence we would have (100/5280)/(2/60^2)=(100/5280)*(60^2/2) miles per hour.

Answer: A.