SOLUTION: a crew of eight can row 20 kilometers per hour in still water. The crew rows upstream and then returns to its starting point in 15 minutes. If the river is flowing a 2 km/h, how f
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Question 262521: a crew of eight can row 20 kilometers per hour in still water. The crew rows upstream and then returns to its starting point in 15 minutes. If the river is flowing a 2 km/h, how far upstream did the crew row?
could you please show me how to set this problem up into an equation? Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! a crew of eight can row 20 kilometers per hour in still water. The crew rows upstream and then returns to its starting point in 15 minutes. If the river is flowing a 2 km/h, how far upstream did the crew row?
:
20 - 2 = 18 km/hr speed upstream
and
20 + 2 = 22 km/hr down stream
;
let d = dist upstream, before turning around
:
Write a time equation: time = dist/speed
Change 15 min to .25 hrs
:
Time upstr + time downst = .25 hrs + = .25
Multiply equation by 396, (that's 18*22). results
22d + 18d = 396(.25)
40d = 99
d =
d = 2.475 km
:
:
Check by finding the times of each leg
2.475/18 = .1375
2.475/22 = .1125
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total time: .25 hrs which is 15 min
