current rate

Question

julie and eric row their boat (at a constant speed) 24 miles downstream for 4 hours, helped by the current. Rowing at the same rate, the trip back against the current takes 6 hours. find the rate of the current

Answer 1

Let r be the rowers' rate and c be the current's rate.

 

rate x time = distance

4(r + c) = 24

6(r - c) = 24

 

4r + 4c = 24

r + c = 6

c = 6 - r

 

6(r - (6 - r)) = 24

12r - 36 = 24

12r = 60

r = 5

c = 6 - 5 = 1

 

The rate of the current is 1 mile per hour.