Excluding stoppages, the speed of a train is 90 km/h and including stoppages it is 75 km/h. How many minutes does the train stop per hour? MCQ with Answer and Explanation
A man can row 9 km/h in still water and he finds that it takes him twice as much time to row up than to row down the same distance. Find the speed of the current.
Explanation:
Let speed of current be c. Downstream speed = 9 + c, Upstream speed = 9 - c. Since time is twice for upstream, speed must be half: 9 - c = (9 + c) / 2 => 18 - 2c = 9 + c => 3c = 9 => c = 3 km/h.
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