12. The traffic lights at three different road crossings change after every 48 sec, 72 sec and 108 sec respectively. If they all change simultaneously at 8 : 20 : 00 hours, then they will again change simultaneously at
8 : 27: 12 hrs 8:27:36 hrs
8: 27: 24 hrs 8:27:48 hrs
Answer: 8 : 27: 12 hrs
Explanation: Interval of change = (1.c.m. of 48, 72, 108) sec. = 432 sec. The lights will change simultaneously after every 432 seconds, i.e. 7 mm. 12 sec.
Next simultaneous change will take place at 8 : 27 : 12 hrs.
