Question
The speed of a boat in still water is 7 km/hr and the
speed of the stream is 2.5 km/hr. A man rows to a place at a distance of 42.75 km and comes back to the starting point. The total time taken by him is:Solution
Rate downstream = (7 + 2.5) kmph = 9.5 kmph Rate upstream = (7 – 2.5) kmph = 4.5 kmph According to the question, Time = Distance/Speed Hence, Required time = 42.75/9.5 + 22.75/4.5 = 4.5 + 9.5 = 14 hours
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