A tugboat goes 120 miles upstream in 20 hours. The return trip downtown takes 5 hours.

Question

Find the speed of the tugboat without a current and the speed of the current.

The speed of the tugboat is ?(mph)

And the speed of the current is what? (mph)

(Simplify your answers)

 

Answer 1

Let v = the speed of the tugboat, and c = the speed of the current.

Balance by the distance

120 = 20(u-c) ==> u-c = 6 .....(1)

120 = 5(u+c) ==> u+c = 24 ......(2)

(1)+(2): 2u = 30 ==> u = 15 mph, c = u-6 = 9 mph <==Answer