Question 132077: There is a train station located at some point on a circular track of radius 30/pi miles. Train A leaves the station at 12:00 traveling 90 mph in the counterclockwise direction. Two and half hours later train B leaves the same station traveling in the same direction but at 85 mph. When train A catches B, how many laps has each train done total?
Answer by kev82(151)   (Show Source):
You can put this solution on YOUR website! The circumference of the circle is 60, right? Train A goes at 90mph so after 2.5 hours will have done 225 miles. This is 3 and 3/4 times round the circle, right? So at the starting time of train B, train A is 1/4 or 15 miles behind it.
Train A travels 5 mph faster than B and has to catch up 15 miles, this will take 3 hours.
So at the time they meet, train A will have gone around for 2.5+3=5.5 hours, at 90mph, which is 495miles, or 8 and 1/4 times. Train B goes round for 3 hours at 85mph, a total of 255 miles which is 4 and 1/4 times round.
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