Question

three bells starts ringing at intervals of 4, 7 and 14 minutes. all three rang at 6 am. when will they ring together again?

Answer 1

The intervals of ringing of these 3 bells are 4,7 and 14 minutes.  

so, Minimum time after which these all 3 bells will ring = LCM(4,7,14) = 28 min.  

so, After 28 minutes , these all 3 bells will ring together.  

And, so, these bells will ring together at 6:28 am.