The Hudson River flows at a rate o 3 mph. A patrol boat travels 60 miles upriver, and returns in a total time of 9 hours. What is the speed of the boat in still water?

Jul 3, 2016

7 mph.

Explanation:

Let v be the speed in still water and t hours be the time for the

journey upstream. Then, time for the journey downstream is (9-t)

hours. Use 'distance = velocity X time'.

Now,sily, (v-3)t=60=(v+3(9-t).

So, $\frac{60}{v - 3} = 9 - \frac{60}{v + 3}$.

This can be simplified to ${v}^{2} = 49$, and so, v=7 mph.