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A, B and C run around a circular track starting from the same point

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A, B and C run around a circular track starting from the same point  [#permalink]

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New post 22 Jul 2016, 03:53
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A
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Question Stats:

63% (02:47) correct 38% (02:23) wrong based on 234 sessions

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A, B and C run around a circular track starting from the same point simultaneously and in the same direction at speeds of 4 kmph, 6 kmph and 8 kmph respectively. If the length of the track is 400 meters, when will A, B and C meet at the starting point for the first time after they started the race?

A. 1 minute
B. 5 minutes
C. 12 minutes
D. 20 minutes
E. 24 minutes

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A, B and C run around a circular track starting from the same point  [#permalink]

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New post 22 Jul 2016, 04:09
take lcm of 4,6,8

24

ans E

till that time A will have 6 revs
b will 4revs and c will have 3 revs
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A, B and C run around a circular track starting from the same point  [#permalink]

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New post 22 Jul 2016, 04:49
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4 kmph, 6 kmph and 8 kmph is equal to 4000/60 mtrs/min, 6000/60 mtrs/min and 8000/60 mtrs/min or 200/3, 100, 400/3 mtrs/min respectively.

Seeing this we can infer that the answer should be at least divisible by 3. (minutes in options are integers. So if the answer is not divisible by 3, we will have 200/3*answer = distance traveled by A in fractions whereas 100*answer = distance traveled by A as integer)

So, A,B and D are out.

At 12 min A,B and C will travel 800, 1200 and 1600 mtrs respectively. Length of the circle is given as 400 mtrs.

As 800, 1200 and 1600 are divisible by 400, we can say that A,B and C will be at starting point after 12 min.

Hence, C will be the answer.

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Re: A, B and C run around a circular track starting from the same point  [#permalink]

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New post 22 Jul 2016, 08:41
hsbinfy wrote:
take lcm of 4,6,8

24

ans E

till that time A will have 6 revs
b will 4revs and c will have 3 revs


we are given values in hour & answers in mins :)
do convert

Ans 12
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Re: A, B and C run around a circular track starting from the same point  [#permalink]

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New post 22 Jul 2016, 08:55
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A: 400 metres in 6 minutes
B: 400 metres in 4 minutes
C: 400 metres in 3 minutes

LCM? 12

Answer C)
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Re: A, B and C run around a circular track starting from the same point  [#permalink]

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New post 22 Jul 2016, 09:54
time taken by A ,B and C to complete a round will be 6,4,3 mins respectively.
LCM of 6,4,3= 12
so they will meet at starting point after 12 mins

ANS C
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Re: A, B and C run around a circular track starting from the same point  [#permalink]

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New post 28 Jul 2016, 11:12
gauravsaggis1 wrote:
time taken by A ,B and C to complete a round will be 6,4,3 mins respectively.
LCM of 6,4,3= 12
so they will meet at starting point after 12 mins

ANS C



Hi!
Can you please explain, how did u get 6, 4 and 3.
Thanks
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Re: A, B and C run around a circular track starting from the same point  [#permalink]

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New post 28 Jul 2016, 13:36
1
Bunuel wrote:
A, B and C run around a circular track starting from the same point simultaneously and in the same direction at speeds of 4 kmph, 6 kmph and 8 kmph respectively. If the length of the track is 400 meters, when will A, B and C meet at the starting point for the first time after they started the race?

A. 1 minute
B. 5 minutes
C. 12 minutes
D. 20 minutes
E. 24 minutes


Respective speed of A, B and C= 4000/60 , 6000/60, 8000/60 km/h

Time required by A= 400 *60/4000= 6 mins
Time required by B= 400*60/6000= 4 mins
Time required by C = 400 *60/8000= 3 mins

Time when these three first meet= LCM of 6, 4 and 3= 12 mins

C is the answer
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Re: A, B and C run around a circular track starting from the same point  [#permalink]

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New post 14 Aug 2016, 05:53
how can you solve the same with the table given in the Gmat club math book
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Re: A, B and C run around a circular track starting from the same point  [#permalink]

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New post 25 Oct 2018, 02:39
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Please suggest if my method to solve this question is right.

Distance is same for A, B and C= 400 meters.
Since they are going in same direction, relative speed can be calculated: 8-6-4= 2kmph

Time = (400/2*1000)*60= 12 min.
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Re: A, B and C run around a circular track starting from the  [#permalink]

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New post 29 Jan 2019, 02:21
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Re: A, B and C run around a circular track starting from the   [#permalink] 29 Jan 2019, 02:21
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