Question 1076229: A pleasure boat sets out for a cruise on a river, sailing upstream 7 miles and then turning around and returning to port. The trip upstream requires 60 minutes and the trip downstream requires 11 minutes. Find the speed of the boat in still water and the speed of the current in miles per hour (mi/h). Round to the nearest whole number.
Answer by jorel1380(3719)   (Show Source):
You can put this solution on YOUR website! Sailing upstream for 7 miles takes 1 hour, or an average rate of 7 miles per hour. Sailing downstream for 7 miles takes 11 minutes, or 11/60 of an hour, making an average rate of 38-2/11 mph. So, let b be the speed of the boat, and c be the speed of the current. Then:
b-c=7 or 77/11
b+c=420/11
Then:
2b=77+420/11
b=497/22=22.591 mph
c=343/22=15.591 mph
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