Subject :IMO Class : Class 6
A, B and C start at the same time in the same direction to run around a circular stadium.
A completes a round in 15 seconds, B in 30 seconds and C in 18 seconds, all starting at the same point. After what time will they meet again at the starting point?
(A) 26 minutes
(B) 140 seconds
(C) 90 minutes
(D) 1 minute 30 seconds