Aptitude - ) In a circular race track of length 100 m, three persons A, B and C start together. A and B start i

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) In a circular race track of length 100 m, three persons A, B and C start together. A and B start in the same direction at speeds of 10 m/s and 8 m/s respectively. While C runs in the opposite at 15 m/s. When will all the three meet for the first time on the after the start?

a) After 4 s

b) After 50 s

c) After 100 s

d) After 200 s

Total Answers and Comments: 4

Last Update: August 05, 2008 Asked by: nurankl84

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Best Rated Answer

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Submitted by: chetan pande

In such type of questions get ur answers from options itself..

take 1st option and calculate distance travelled by each person so it will be (4*10)=40m for A,(4*8)=32,(4*15)=60............so here distance travelled by each person is not a Multiple of 100 .....

likewise try for other options ................

The correct answer is 100s

Above answer was rated as good by the following members:
piyush_dnma, r.praveenkumar

August 02, 2006 05:41:43

chetan pande

RE: ) In a circular race track of length 100 m, three ...

In such type of questions get ur answers from options itself..

take 1st option and calculate distance travelled by each person so it will be (4*10)=40m for A,(4*8)=32,(4*15)=60............so here distance travelled by each person is not a Multiple of 100 .....

likewise try for other options ................

The correct answer is 100s

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1 0

Overall Rating: +1

August 05, 2006 17:39:40

Basheer

RE: ) In a circular race track of length 100 m, three ...

Yes it is C) after 100s

In 100 sec A completes 10 cycles.

B completes 8 cycles.

C completes 15 cycles.

D) after 200 sec also, all the three will be at same place but this is not the first time.

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Overall Rating: +2

July 15, 2008 00:51:48

rajesh0457

Member Since: July 2008 Contribution: 1

RE: ) In a circular race track of length 100 m, three persons A, B and C start together. A and B start in the same direction at speeds of 10 m/s and 8 m/s respectively. While C runs in the opposite at 15 m/s. When will all the three meet for the first tim

A takes (100m) / (10m/s) = 10s to finish one complte round.

B takes (100m) / (8m/s) = 12.5s to finish one complte round.

C takes (100m) / (15m/s) = (20/3)s to finish one complte round.

For them to meet, the time will be LCM of above three times

ie LCM(10,12.5,20/3)=

                                 = LCM(10/1,25/2,20/3)
                                 = LCM(10,25,20)/GCD(1,2,3)
                                 = 50/1
                                 = 50 seconds.

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August 05, 2008 08:56:49

manoj21988

Member Since: August 2008 Contribution: 1

Here considering the same direction they meet for the first time when A overtakes B as well as A overtakes C simultaneously for the first time

Thus, A overtakes B every 50 seconds

A overtakes C every 4 seconds (100/25)
LCM is 100 seconds
After 100 seconds, A travels 1000m(reaches start point), B 800m(start pt), C 1500m(aftr 15 rounds reaches start pt again)
Thus its 100s at the start

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