SOLUTION: Problem Solving Using Systems of Equations Julie and Eric row their boat(at a constant speed) 55 miles downstream for 5 hours, helped by the current. Row at the same rate, the t

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons -> SOLUTION: Problem Solving Using Systems of Equations Julie and Eric row their boat(at a constant speed) 55 miles downstream for 5 hours, helped by the current. Row at the same rate, the t      Log On


   

Question 6302: Problem Solving Using Systems of Equations
Julie and Eric row their boat(at a constant speed) 55 miles downstream for 5 hours, helped by the current. Row at the same rate, the trip back against the current takes 11 hours. Find the rate of the current.
Answer by xcentaur(357) About Me  (Show Source):
You can put this solution on YOUR website!
let the speed of their rowin be x mph
let the speed of the current be y mph


then speed downstream=(x+y)mph
distance=55 miles
time=5 hours
speed=d/t=55/5=11 mph
therefore,(x+y)=11


speed upstream=(x-y)mph
distance=55 miles
time taken=11 hours
speed=d/t=55/11=5 mph
therefore,(x-y)=5 mph


Now we have a system of equations:
x+y=11
x-y=5


Solved by pluggable solver: Linear System solver (using determinant)
Solve:
+system%28+%0D%0A++++1%5Cx+%2B+1%5Cy+=+11%2C%0D%0A++++1%5Cx+%2B+-1%5Cy+=+5+%29%0D%0A++

Any system of equations:


has solution

or



(x=8, y=3}


Thus we get,
(x=8, y=3}


Hence speed of current: 3 mph


Prabhat.