Three runners : Do they ever meet??

Replies

• 

  YOUNGGRASSHOPPER

  I will go with a.
• 

  Sachin Jain

  @ Young Grass Hopper
  Can you please explain your approach.
• 

  Saandeep Sreerambatla

  They will meet after 100 sec.
  by back substitution I have solved this.
  
  According to the options, if we go for b. Then A travels 500m , and b 400m and C - 750m. A and B are at the start point but not C.
  
  So after 100 sec they will meet.
• 

  freak16

  Can u plz explain your approach??
• 

  Sachin Jain

  @ freak16
  I got English scared is trying to say.
  I think he used options and tried to satisfy which option suited best.
  Firstly create an image of race track in your mind. That is it is circular and 100 m in length
  A,B,C are at starting points but run in different directions with different speeds.
  This is the scenario.
  
  Now take Option (a) 4s
  A-> 40m
  B-> 32m
  c-> 60m
  That means A and C meet in this case but B does not.
  So this option is wrong
  
  Now take Option B
  A->500
  B->400
  c->750
  
  A and B come back at the starting points but C is in half way of track.
  So this is also wrong
  
  This way go on and you will get the answer.
  I hope i am clear....
• 

  freak16

  @Es
  You rock!!
  can u plz tell me their second meet will be after 200s and like that they will meet after every 100 sec..
  M i right??
• 

  freak16

  @blunderboy
  plz reply to my above post..😀
• 

  YOUNGGRASSHOPPER

  I took the 100m circle track and devided it in half. With A abnd B running one direction and C running in the opposing the total distance that has to be covered by group A B and group C is still 100m before they meet the first time.
  
  A) will travel 40m in 4s. 4s times 10m/s
  
  B) will travel 32m in 4s. 4s times 8m/s
  
  C) will travel 60m in 4s. 4s times 15m/s
  
  A and C will be the first to meet in 4s and B and C will still be 8m from first point of contact.
  
  That is why I chose Answer a) After 4s.
• 

  Sachin Jain

  @freak16 Yes you are right....😀
• 

  ChaZ-E

  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(60,75,40)/LCM(1,2,3)
  =600/6
  =100sec
• 

  Shashank Moghe

  After 100 seconds, at the starting point.