Problema Solution
JULIE AND ERIC ROW THEIR BOAT (AT A CONSTANT SPEED) 40 MILES DOWNSTREAM FOR 4 HOURS, HELPED BY THE CURRENT. ROWING AT THE SAME RATE, THE TRIP BACK AGAINST THE CURRENT TAKES 10 HOURS. FIND THE RATE OF THE CURRENT.
Answer provided by our tutors
let
v = the rate of the boat in still water
c = the rate of the current
t1 = 4 hr time of the travel downstream
d = 40 mi downstream travel distance
t2 = 10 hr the time of the return trip upstream
the boats speed downstream: v + c
the boats speed upstream: v - c
since speed = distance/time we have
traveling downstream
v + c = d/t1
v + c = 40/4
v + c = 10
traveling upstream
v - c = d/t2
v - c = 40/10
v - c = 4
by solving the system of equations
v + c = 10
v - c = 4
we find:
v = 7 mph
c = 3 mph
click here to see the step by step solution of the system of equations:
the rate of the current is 3 mph.