Three friends started running together on a circular track at 8:00:00 am. Time…
2023
Three friends started running together on a circular track at 8:00:00 am. Time taken by them to complete one round of the track is 15 min, 20 min, 30 min respectively. If they run continuously without any halts, then at what time will they meet again at the starting point for the fourth time ?
- A.
8:30:00 am
- B.
9:00:00 pm
- C.
12:00:00 pm
- D.
12:00:00 am
Attempted by 30 students.
Show answer & explanation
Correct answer: C
Answer:
12:00:00 pm
Explanation:
Compute the least common multiple of the lap times: LCM(15, 20, 30) = 60 minutes.
They all return together to the starting point every 60 minutes (every 1 hour).
Meeting times after the start at 8:00:00 am are: 9:00:00 am (after 1 hour), 10:00:00 am (after 2 hours), 11:00:00 am (after 3 hours), and 12:00:00 pm (after 4 hours).
Therefore, the fourth time they meet at the starting point is 4 hours after 8:00:00 am, i.e., 12:00:00 pm (noon).