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# A boat travels at the speed of 15 km/hr in still water.

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Senior Manager
Joined: 30 Aug 2003
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A boat travels at the speed of 15 km/hr in still water. [#permalink]

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16 Jan 2004, 14:35
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

A boat travels at the speed of 15 km/hr in still water. However, it will take three times as long for the boat to row up stream as to row downstream. What is the speed of the stream?

a. 5 kmph
b. 7.5
c. 9
d. 10
e. Cannot be determined
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Pls include reasoning along with all answer posts.
****GMAT Loco****
Este examen me conduce jodiendo loco

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Senior Manager
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16 Jan 2004, 14:45
Ans:7.5
sol:
rate upstream =x
downstream=3x

rate in still water =1/2(x+3x)=2xkm/hr
2x=15 ,x=7.5
so 3x=22.5
rate of stream=1/2(22.5-7.5)=7.5
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shubhangi

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16 Jan 2004, 15:06
I have a little bit different approach: X-speed of current
15-X/15+X=1/3
15+X=45-3X
4X=30
X=7,5

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16 Jan 2004, 15:18
Nice BG. Or again, as PR relentlessly taught us, we can just backsolve and find it in 20 seconds
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Best Regards,

Paul

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16 Jan 2004, 15:18
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