Quantitative Aptitude – TSD – Four friends, Ashish, Brian, Chaitra


XAT 2021 Exam Paper – Quantitative Aptitude – TSD – Four friends, Ashish, Brian, Chaitra

Q. Four friends, Ashish, Brian, Chaitra, and Dorothy, decide to jog for 30 minutes inside a stadium with a circular running track that is200 metres long. The friends run at different speeds. Ashish completes a lap exactly every 60 seconds. Likewise, Brian, Chaitra and Dorothy complete a lap exactly every 1 minute 30 seconds, 40 seconds and 1 minute 20 seconds respectively. The friends begin together at the start line exactly at 4 p.m. What is the total of the numbers of laps the friends would have completed when they next cross the start line together ?
  1. 47
  2. 28
  3. 43
  4. They will never be at the start line together again before 4:30 p.m.
  5. 36

Answer: 47

Solutions:
All the four friends will meet at the starting point after LCM(60,90,40,80) = 720 seconds.

Number of laps by Ashish in 720 seconds = 720/60 =12
Number of laps by Brian in 720 seconds = 720/90 = 8
Number of laps by Chaitra in 720 seconds =720/40 = 18
Number of laps by Dorothy in 720 seconds = 720/80 = 9
Together they complete = 12+8+18+9 = 47 laps

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