Question

One day last summer, Jim went kayaking on the Little Susitna River in Alaska. Paddling upstream against the current, he traveled 12 miles in 3 hours. Then he turned around and paddled twice as fast downstream and, with the help of the current, traveled 17 miles in 1 hour. Find the rate of the current.

Answer 1

6.5 miles per hour

Explanation:

At first, Jim was paddling against the current for 3 hours. Then, he paddled for 1 hour with the help of the current.

Let x be Jim's rate without the current and y be the rate of the current:

`(x-y)*3=12\\(x+y)*1=17`

By solving the linear system, we can find the rate of the current y:

`x=17-y\\(17-y-y)*3=12\\y=(39)/(6)\\y=6.5\ (miles)/(hour)`

The current has a rate of 6.5 miles per hour.