Question
Train A crosses a stationery train B in 50 seconds and a pole in 20 seconds with the same speed. The length of train A is 240 meters. What is the length of the stationery train B?
Solution
Time to cross the pole = ${\text"length of train"}/{\text"speed of train"}$, which gives ${240/v}$ = 20, so v = 12. If the required length of the standing train = x, then by the "train bridge" formula, ${x + 240}/12 = 50$, which gives x = 360 meters.
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