What was the rate of the current? What was their average speed in still water?

Question

It took lance and Ivan 6 hours to travel 33 miles downstream by canoe on the Mississippi river. The next day they traveled 8 hours upstream for 20 miles.

Answer 1

Let c= speed of current and v=speed of canoe, their speed is v+c downstream and v-c upstream.

33=6(v+c) and 20=8(v-c).

33=6v+6c and 20=8v-8c.

So 11=2v+2c and 5=2v-2c; adding these: 16=4v so v=4mph.

And c=½(8-5)=1.5mph.

Canoe speed=4mph, speed of the current=1.5mph.