The ratio of the speed of a boat to the speed of the current of water is 36 : 5. The boat goes a certain distance downstream in 5 hours 10 minutes. How much time will it take to come back against the stream?
6 hours 50 minutes
Let boat speed = 36k, current speed = 5k.
Downstream speed = 41k, upstream speed = 31k. Downstream time = 5 hours 10 minutes = 310 minutes.
Distance = 41k × 310. Upstream time = Distance/(31k) = (41 × 310)/31 = 410 minutes = 6 hours 50 minutes.
Hence, the boat will take 6 hours 50 minutes to come back against the stream.
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