2021 · Q15
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 ?
Elementary MathematicsHCF and LCM
- AAfter 3 hour 30 minutes
- BAfter 4 hour 30 minutes
- CAfter 3 hours
- DAfter 7 hours
Explanation
The runners meet again at the starting point after a whole number of laps each, i.e. after LCM(20, 30, 35) minutes. LCM(20, 30) = 60 and LCM(60, 35) = 420. 420 minutes = 7 hours. This is option (d).