SOLUTION: A canoe takes 7 hours to travel 48 kilometres down a river and back.The rate of the current of the river is 2 kilometres per hour.Find the rate of the canoe in still(calm) water.

 

Hi

A canoe takes 7 hours to travel 48 km down a river and back.The rate of the current of the river is 2 kmph.

Find the rateof the canoe in still(calm) water.

 D =rt   or  D/r = t

     |Multiplying thru by (r+2)(r-2)so as all denominators = 1

   48(r-2) + 48(r+2) = 7(r+2)(r-2)

         96r = 7(r^2 - 4)

            7r^2 - 96r - 28 = 0  

             (7r+2)(r - 14) = 0  |throwing out negative solution for rate

                       r = 14 kmph is the speed of the canoe in still(calm) water.

CHECKING our Answer***

    = 3hr + 4hr = 7hr