SOLUTION: Debbie traveled by boat 5 miles upstream to fish in her favorite spot. Because of the 4 mile per hour current, it took her 40 minutes longer to get there than to return. How fast w

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Question 48835: Debbie traveled by boat 5 miles upstream to fish in her favorite spot. Because of the 4 mile per hour current, it took her 40 minutes longer to get there than to return. How fast will her boat go in still water? (Please round answer to one decimal place.)
Answer by Paul(988) About Me  (Show Source):
You can put this solution on YOUR website!
LEt x represent the speed of the boat
EQUATION:
5%2F%28x-4%29-5%2F%28x%2B4%29=2%2F3
5%28%28x%2B4%29-%28x-4%29%29=%282%28%28x%2B4%29%28x-4%29%29%29%2F3
5%288%29=%282%28x%5E2-16%29%29%2F3
40=%282x%5E2-32%29%2F3
120=2x%5E2-32
x=8.7
Hence, the speed of the boat is 8.7mph
Paul.