Balu travels at the speed of 18 kmph in still water. If the rate of current is 3 kmph, what time will he save in travelling 315 km, if he had to travel with the stream instead of against the stream ?
Speed upstream = (18-3) = 15 kmph,
Speed down stream = (18+3) = 21 kmph
Time taken for upstream = 315/15 = 21 hrs.,
Time taken for down stream = 315/21 = 15 hours.
.'. Balu will save 6 hours(21 -15), if he had travel with the stream instead of against the stream.
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