A man swims downstream 72 km and upstream 45 km taking 9 hours each time; what is the speed of the current?

2 Answers on this Question

1. Upstream 45km/ 9 hrs downstream 72 km/ 9 hrs.
   Downstream speed 8km/hr. Upstream 5 km/hr
   Speed in still water = (8+5)/2=6.5 km/hr
   8-6.5 or 6.5-5 =1.5 km/hr is the speed of current.

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2. Explanation:

   72 — 9
   ? —- 1

   => Down Stream = 8

   45 —- 9
   ? —- 1

   => Up Stream = 5

   Speed od current S = ?

   S = (8 – 5)/2 = 1.5 kmph.

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