Question
Speed of a boat in still water is 15 kmph and speed of stream is 12 kmph. A man rows to a place at a distance of 81 km and come back to starting point. The total time taken by him is:
Solution
Rate upstream = 15 – 12 = 3 kmph Rate downstream = 15 + 12 = 27 kmph Time taken to go upstream = 81/3 = 27 hr Time taken to go downstream = 81/27 = 3 hr Total time = 27 + 3 = 30 hrs
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