Question

Boris is kayaking in a river with a 6mph current. Suppose that he can kayak4 miles upstream in the same amount oftime as it takes him to kayak 9 milesdownstream. Find the speed (mph) ofBoris’s kayak in still water.

Answer 1

We will have to solve as follows:

*Since we know that the downstrean speed is 6mph, then we will want to know how much time will take to go 9 miles downstream, that is:

`t=(9\cdot1)/(6)\Rightarrow t=1.5`

Now, we know he takes 1.5 hours to move 9 miles downstream. With this information, we will solve for the speed he needs to move at in order to translate 4 miles uptream, that is:

`v=(4)/(1.5)\Rightarrow v\approx2.67`

He will then, move at aproximately 2.67 miles per hour while going upstream.

That is because he will cover the same ammount of time, but will cover a shorter distance.