2019 · Q17
X, Y and Z start at some point and same time in the same direction to run around a circular stadium. X completes a round in 252 seconds, Y in 308 seconds and Z in 198 seconds. After what time will they meet again at the starting point?
Elementary MathematicsHCF and LCM
- A26 minutes 18 seconds
- B42 minutes 36 seconds
- C45 minutes
- D46 minutes 12 seconds
Explanation
They meet again after LCM(252, 308, 198) seconds. 252 = 2^2x3^2x7, 308 = 2^2x7x11, 198 = 2x3^2x11, so LCM = 2^2x3^2x7x11 = 2772 s = 46 minutes 12 seconds.