Problema Solution

In still water a boat averages 8 miles per hour. It takes the same amount of time to travel 16 miles downstream, with the current, as it does 8 miles upstream, against the current. What is the rate of the water's current

Answer provided by our tutors

let


v = 8 mph the rate of the boat in still water

d1 = 16 mi the distance downstream

d2 = 8 mi the distance upstream

t = the time of the travel upstream = the time of the travel downstream

c = the rate of the water's current


the rate of the boat traveling downstream is: v + c


since rate = distance/time we have


v + c = d1/t


8 +c = 16/t


t = 16/(8 + c)


the rate of the boat traveling upstream is: v - c


v - c = d2/t


8 - c = 8/t


plug t = 16/(8 + c) into the last equation


8 - c = 8/(16/(8 + c))


we find


c = 8/3


c = 2.67 mph


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the rate of the water's current is 2.67 mph.