Problema Solution

A motorboat with the current went 72mi in 4 hours. Against the current, the motorboat could go only 40 mi in the same amount of time. Find the rate of the motorboat in calm water.

Answer provided by our tutors

Speed of = x

Speed of watr = y

So speed with current = x+y = 72/4 = 18

or x+y =18

Speed against water = x-4 = 40/4=10

or x-y =10

So 2x=28

or x=14

So rate of motorbaot in calm water = 14 miles/hour