SOLUTION: It took 3 hours to row a boat 18 km against the current. The return trip with the current took 1 1/2 (1.5) hours. Find the speed of the rowboat in still water.
I already tried
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Question 392239: It took 3 hours to row a boat 18 km against the current. The return trip with the current took 1 1/2 (1.5) hours. Find the speed of the rowboat in still water.
I already tried:
d = 3(r-18) d = 1.5(r+18)
d = 3r - 54 d = 1.5r + 27
3r - 54 = 1.5r + 27
3r = 1.5 = 81
1.5r = 81
r = 54 km/hr
d = 3(54-18)
d = 3(36)
d = 108 km
d = 3*54-54
d = 108 km
But the speed of the rowboat in still water can't be 54 km/hr, can it? Answer by Alan3354(69443) (Show Source):
You can put this solution on YOUR website! 18/3 = 6 km/hr
18/1.5 = 12 km/hr
The boat's speed is the average = (6 + 12)/2 = 9 km/hr
The current speed is the difference = 3 km/hr
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I already tried:
d = 3(r-18) d = 1.5(r+18)
d = 3r - 54 d = 1.5r + 27
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If you include units, you'll see that your approach is not right.
d = 3(r-18) d = 1.5(r+18)
r-18 --> km/hr - km The units don't match, so something's wrong. Using the units can help to avoid mistakes.
