Two cyclists begin training on an oval racecourse at the same time.The professional cyclist completes each lap in 4 minutes; the novice takes 6 minutes to complete each lap. How many minutes after the start will both cyclists pass at exactly in the 15th lap,at the same spot where they began to cycle?
(a) 12
(b) 165
(c) 180
(d) 24

• cyclist cover 15 lap in 4*15=60 min
  novice cover 15 lap in 6*15=90 min
  so after 15 lap they meet at the same pt from where they start LCM(60,90)=180 min
• 12 years agoHelpfull: Yes(25) No(16)
• This question is asking you to find the LCM (Lowest common multiple) of 4 and 6.
  Prime factors of 4: 2*2
  Prime factors of 6: 2*3
  
  LCM = 2*2*3 = 12
• 12 years agoHelpfull: Yes(19) No(9)
• they wil meet 4r 1st time at startng pt at LCM of 4 and 6 i.e 12
  but to meet in the 15th lap 15*12=180min
  
• 12 years agoHelpfull: Yes(5) No(3)
• but it is asked that when they will pass in 15th lap.
  in 12 minutes only 3 laps will be completed..so answer should be 60 ???
• 12 years agoHelpfull: Yes(2) No(5)
• take L.C.M 6,4
  ans is 12
• 12 years agoHelpfull: Yes(2) No(4)
• for two laps thenovice takes 12minutes and for cyclist in 12 minutes he completes 3 laps exactly so the answer is 12minutes
• 12 years agoHelpfull: Yes(1) No(5)
• First they meet in 12 min.
  and every time they will meet exact after 12 min.(because..1st case 4,8,12,16,20,24....and 2nd case 6,12,18,24.....)
  Now question is how many minute after the start both cyclist pass exactly 15 lap at the same spot?
  Therefore it was 12 X 15=180
• 9 years agoHelpfull: Yes(1) No(0)