The traffic lights at four different road crossings change after every 15 sec, 18 sec, 27 sec and 30 sec respectively. If they all change simultaneously at 6 : 10 : 00 hours, then at what time will they again change simultaneously?

The traffic lights at four different road crossings change after every

1.	The traffic lights at four different road crossings change after every 15 sec, 18 sec, 27 sec and 30 sec respectively. If they all change simultaneously at 6 : 10 : 00 hours, then at what time will they again change simultaneously?
A.	6 : 14 : 30 hours
B.	6 : 40 : 00 hours
C.	6 : 14 : 00 hours
D.	10 : 40 : 00 hours
Answer» B. 6 : 40 : 00 hours