Three runners are running in a circular track, and they complete one round in 20, 30 and 35 minutes respectively. When will they next meet at the starting point?
- A. After 3 hour 30 minutes
- B. After 4 hour 30 minutes
- C. After 3 hours
- D. After 7 hours ✓
Correct Answer: D. After 7 hours
Explanation
They will meet again at the LCM of their individual times. \text{LCM}(20, 30, 35) = 420 minutes. Converting this to hours: 420 \div 60 = 7 hours.
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