In still water a boy rows 5 miles an hour. With the aid of current he can make a 21 miles trip in 3 hours. How fast is the current?

In still water a boy rows 5 miles an hour. With the aid of current he can make a 21 miles trip in 3 hours. How fast is the current? Correct Answer 2 miles

Water = 5 miles/hourWater + Current = 21 miles/3 hours                                 = 7 miles/hour So, Current = (7-5) miles/hour                      = 2 miles/hour (Ans)
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