Problema Solution
traveling upstream against the current man traveled 21 miles in 3 hours. he turned around and paddled twice as fast downstream, with the help of the current he traveled 20 miles in 1 hour. find the rate of the current.
Answer provided by our tutors
Let
v = the rate of the paddling upstream
2v = the rate of the paddling downstream
c = the rate of the current
d1 = 21 mi the distance traveled upstream
d2 = 20 mi the distance traveled downstream
t1 = 3 hr the time of the travel upstream
t2 = 1 hr the time of the travel downstream
traveling upstream the rate of the boat is: v - c
v - c = d1/t1
v - c = 21/3
v - c = 7
traveling downstream the rate of the boat is: 2v + c
2v + c = d2/t2
v + c = 20/1
v + c = 20
by solving the system of equations:
v - c = 7
v + c = 20
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c = 6.5 mph
The rate of the current is 6.5 mph.