Find the crews rowing rate and in still water and the rate of the current.

Question

If a boats crew rowed 9 miles downstream with the current, in 1.5 hours. The return trip upstream, against the current, covered the same distance, but took 3 hours. Find the crews rowing rate and in still water and the rate of the current.

Answer 1

Let x = rowing speed in still water

     y = speed of current

 

Then, x + y = speed downstream

         x - y = speed upstream

 

Distance = (Rate)(Time)

 

1.5(x + y) = 9

  3(x - y) = 9

 

Divide the first equation by 1.5 and the second equation by 3:

 

x + y = 6

x - y = 3

 

Add the equations:  2x = 9

 

                              x = 4.5 mph (rowing speed)

                              y = 1.5 mph (speed of current)