The traffic lights at 3 different roads change after every 12 sec, 15 sec, 21 sec respectively. If they all change simultaneously at 8 AM then at what time will they again change simultaneously. Select
A) 8:15 B) 8:42 C) 8:07 D) 9:01 E) 9:15
L8:07M of 12,15,21 = 420 = 7mnts   The lines will change every 7m   The light will change again after 8 AM is = 9:00+0:07 = 8:07   Answer is 8:07
<result>C</result>
The traffic lights at 3 different roads change after every 12 sec, 15 sec, 21 sec respectively. If they all change simultaneously at 8 AM then at what time will they again change simultaneously.