Question 714579
If a man is kayaking upstream, and the river has a velocity of 2km/hr downstream, how fast must the man paddle to move upstream at a velocity of 5km/hr? 
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Ans: To go 5 km/hr against a 2 km/hr stream the man has to
paddle at a rate of 5+2 = 7 km/hr
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Cheers,
Stan H.