Question

seven bells ring at intervals of 2,3,4,6,8,9 and 12 minutes respectively. they started ringing simultaneously at 6.00 in the morning. how many more times would all the seven bells ring simultaneously till 5 in the evening of the same day?

Answer 1

Nine times. 
6 am till 5 pm is 11 hours, i.e., 11 x 60= 660 minutes.

LCM of 2,3,4,6,8,9, and 12= 72 
that means the bells will ring simultaneously at a minimum of 72 minutes.
 660 divided by 72 = 9.something.
 which means the bells will ring simultaneously for nine times in 11 hours (before 5 in the evening).

HOPE THIS HELPS!