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In a 100m, A beats B by 15m and B beats C by 10m. If A beats C by 5 se

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In a 100m, A beats B by 15m and B beats C by 10m. If A beats C by 5 se  [#permalink]

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06 Jun 2016, 20:23
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Difficulty:

95% (hard)

Question Stats:

44% (02:18) correct 56% (02:27) wrong based on 78 sessions

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In a 100m, A beats B by 15m and B beats C by 10m. If A beats C by 5 sec then the speed of C.

A. 5m/sec
B. Speed of C can not be found with given data.
C. 4.7m/sec
D. 4m/sec
E. 4.5m/sec
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Joined: 02 Aug 2009
Posts: 6797
Re: In a 100m, A beats B by 15m and B beats C by 10m. If A beats C by 5 se  [#permalink]

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06 Jun 2016, 20:53
anceer wrote:
In a 100m, A beats B by 15m and B beats C by 10m. If A beats C by 5 sec then the speed of C.

A. 5m/sec
B. Speed of C can not be found with given data.
C. 4.7m/sec
D. 4m/sec
E. 4.5m/sec

Hi,

Its more of a Indian CAT Qs than a GMAT Qs.....

Anyways the solution is.....

When A finishes the race , B is at 85m....
and when B travels 100m, C is at 100-10 = 90m.....
so C loses 10m on B's 100m................
or C will lose 1 m for every 10m of B.....
so C will lose 8.5 m when B travels 85m.....

From above we get corelation of all three..
A is at 100, B is at 85 and C is at 85-8.5 = 76.5.....

So C is 100-76.5 = 23.5 m behind A...
and C also loses by 5 secs, this means C covers this 23.5m in 5 secs..
speed of C =$$\frac{23.5}{5} = 4.7$$ mps

C
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Re: In a 100m, A beats B by 15m and B beats C by 10m. If A beats C by 5 se  [#permalink]

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06 Jun 2016, 22:53
anceer wrote:
In a 100m, A beats B by 15m and B beats C by 10m. If A beats C by 5 sec then the speed of C.

A. 5m/sec
B. Speed of C can not be found with given data.
C. 4.7m/sec
D. 4m/sec
E. 4.5m/sec

Here are a couple of posts on races:
http://www.veritasprep.com/blog/2014/08 ... re-higher/
http://www.veritasprep.com/blog/2014/09 ... -on-races/
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Veritas Prep GMAT Instructor

GMAT self-study has never been more personalized or more fun. Try ORION Free!

Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 8284
Location: Pune, India
Re: In a 100m, A beats B by 15m and B beats C by 10m. If A beats C by 5 se  [#permalink]

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16 Oct 2017, 11:46
2
anceer wrote:
In a 100m, A beats B by 15m and B beats C by 10m. If A beats C by 5 sec then the speed of C.

A. 5m/sec
B. Speed of C can not be found with given data.
C. 4.7m/sec
D. 4m/sec
E. 4.5m/sec

Responding to a pm:

In the same time, A covers 100m and B covers 85 m.
SpeedA : SpeedB = 100:85 = 20:17

In the same time, B covers 100m and C covers 90m.
SpeedB : SpeedC = 100:90 = 10:9

SpeedA : SpeedB : SpeedC = 200:170:153
A covers 200m in the time that C covers 153 m so in a 100 m race, when A finishes, C would have covered 76.5 m. Since A beats C by 5 secs, C covers the leftover 23.5 m in 5 secs.
Speed of C = 23.5/5 = 4.7 m/s

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Karishma
Veritas Prep GMAT Instructor

GMAT self-study has never been more personalized or more fun. Try ORION Free!

Re: In a 100m, A beats B by 15m and B beats C by 10m. If A beats C by 5 se &nbs [#permalink] 16 Oct 2017, 11:46
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