Question
The speed of current is 5 km/h. What will be the
respective downstream speed and upstream speed of a boy rowing a boat, if half of the distance covered going downstream in a certain time is equal to the distance covered going upstream in the same time?Solution
Let the speed of boy in still water be X km/h. And the speed of current = 5 km/h Downstream speed = (X + 5) km/h Upstream speed = (X – 5) km/h Let time be ‘t’ hours. ⇒ [(X + 5) t]/2 = (X – 5) t ⇒ X + 5 = 2X – 10 ⇒ X = 15 km/h Downstream speed = 15 + 5 = 20 km/h Upstream speed = 15 – 5 = 10 km/h
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