In a circular 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 after the start?

• 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)
  =100/1
  =100
• 9 years agoHelpfull: Yes(26) No(1)
• ans:100s
  For A & B,
  t=100/(10-8)
  t=50s
  A and B meet after every 50s.
  After second 50s,C travels 1500m.
  so A,B,C meet every 100s.
• 9 years agoHelpfull: Yes(9) No(3)
• 100s these type of question shoul b solved by using the examples. the options are 4s, 50s,100s,200s. so 4*10+4*8+4*15=132 which is nt the multiple of 100.. similarly check for others. 100s will b d 1st tme when they vll meet. through 200 also also 100 multiple will come bt it vll nt the first tme.
• 9 years agoHelpfull: Yes(6) No(3)
• 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.
• 9 years agoHelpfull: Yes(6) No(8)
• after 100s, In 100 sec A completes 10 cycles.B completes 8 cycles. C completes 15 cycles.
  Best way is check options
• 9 years agoHelpfull: Yes(5) No(3)
• M.R Priya .. it should be d multiple of 100 becoz tracks length is 100m...
• 9 years agoHelpfull: Yes(2) No(1)
• y it should be 100 multiple.....
• 9 years agoHelpfull: Yes(1) No(1)
• @shrey lcm(10,25,20) is 100, not 50.
• 9 years agoHelpfull: Yes(0) No(0)