Query Detail : RBI Grade B Phase I

Six bells commence tolling together and tolls at intervals of 2, 3, 4, 5, 6 and 10 seconds respectively. In 30 minutes, how many times do they toll together? My Answer : 30 Correct Answer : 31
Garima,   October 24th 2019,  
RBI Grade B Phase I


LCM = 60 S

So they are tolling together at a inerval of 1 minute. Hence in 30 min, all bells will toll togther 30 times but at starting they also toll togther so final asnwer = 30+1 = 31