Question 682308
A freight train leaves a station traveling 60 miles per hour.  Thirty minutes later a passenger train leaves the station in the same direction on a parallel track at a speed of 72 miles per hour.  How long will it take the passenger train to catch the freight train?
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In 30 mins (1/2 hr) the 1st train has gone 30 miles (60*1/2)
The 2nd train gains on the 1st at 12 mi/hr (72-60)
30 mi/12 mi/hr = 2.5 hours.