Traffic lights at 3 different roads crossing changes after 48 sec, 72 sec, 108 sec. If they all change together at 8:20 am then at what time they will change again?
Answer & explanation
Correct answer: option 2
L.C.M. of 48, 72 & 108 = 432 (sec.) = 7 min 12 sec.
They will ring together again (8: 20 + 7min 12sec.) = 8 : 27 : 12 am.