Princeton review CAT1

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Princeton review CAT1

by kaf » Thu Mar 19, 2009 1:46 am
Can somebody please explain why the answer to this question is A

thanks

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)
Source: — Problem Solving |

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by avenus » Thu Mar 19, 2009 3:06 am
speed will be 100/2 feet per second

in miles per hour: (100/5280)/(2/60^2) which is the same as a)

There are 60^2 seconds in an hour, so 2 seconds will be 2/60^2 hours