Problema Solution
on a weekend outing, carlos rents a motorboat for 10hrs travel down the river and back. the rental operator tells hom to go 4hrs downstream, leaving 6hrs to return upstream. if the river flow stream is 6mph how fast would carlos travel in order to return in 10hrs?
Answer provided by our tutors
let
t1 = 4 hr the time of the travel downstream
t2 = 6 hr the time of the travel upstream
r = 6 mph the river flow stream
v = the speed of the motorboat in still water
the speed of the boat downstream is: v + r
the speed of the boat upstream is: v - r
since distance = speed*time
the distance downstream = the distance upstream
(v + r)*t1 = (v - r)t2
(v + 6)4 = (v - 6)6
by solving we find
v = 30 mph
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Carlos motorboat would have to travel with a speed of 30 mph in still water.