Symbiosis National Aptitude Test SNAP 2016 Paper

L.C.M. of 6, 5, 7, 10 and 12 is 420.
So, the bells will ring together after every 420 seconds i.e. 7 minutes.
Now, 7 × 8 = 56 and 7 × 9 = 63.
Thus, in 1 hour (or 60 minutes), the bells will toll together 8 times, excluding the one at the start.