Math CentralQuandaries & Queries


Question from Carl:

If you can row 3 mph in still water and paddle 3 miles upstream and return in 3.6 hours then what is the speed of the current?

Hi Carl,

The key to this problem is that rate is distance divided by time, (rate = distance/time) in your case miles divided by hours. Thus time = distance/rate.

Suppose the speed of the current is s mph. When you paddle upstream (against the current) your speed is 3 - s mph. You travel upstream for 3 miles so the time used is

upstream time = 3/(3 - s) hours.

When you travel downstream (with the current) what is your speed? What is the downstream time? The total time is 3.6 hours. Solve for s.

If you have trouble completing this problem write back,

About Math Central


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.
Quandaries & Queries page Home page University of Regina PIMS