SOLUTION: A motorboat traveling with the current went 72 miles in 3 hours. Against the current, the boat could only go 48 miles in the same amount of time. Find the rate of the current is 4

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: A motorboat traveling with the current went 72 miles in 3 hours. Against the current, the boat could only go 48 miles in the same amount of time. Find the rate of the current is 4       Log On


   

Question 1118535: A motorboat traveling with the current went 72 miles in 3 hours. Against the current, the boat could only go 48 miles in the same amount of time. Find the rate of the current is 4 miles per hour
Found 2 solutions by ikleyn, Alan3354:
Answer by ikleyn(52879) About Me  (Show Source):
You can put this solution on YOUR website!
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The effective speed downstream is 72%2F3 = 24 miles per hour.

It is the sum of the motorboat own speed relative to water and the current speed:


24 = u + v     (1)


The effective speed upstream is 48%2F3 = 16 miles per hour.

It is the difference of the motorboat own speed relative to water and the current speed:


16 = u - v.    (2)


Thus you have these two equations

u + v = 24
u - v = 16


Add them to get

2u = 24 + 16 = 40  ====>  u = 40/2 = 20


and then from eq(1)  get  v = 24 - 20 = 4.


Answer.  The rate of the current is  4 miles per hour.

Solved.


Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
A motorboat traveling with the current went 72 miles in 3 hours. Against the current, the boat could only go 48 miles in the same amount of time. Find the rate of the current is 4 miles per hour
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Find what?
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The current is 4 mi/hr.