A bells toll together at 9:00am. They toll after 7,8,11and12 seconds respectively . How many times will they toll together again in the next 3 hours.
Answers
Step-by-step explanation:
Bell1 : tolls at t = 0seconds, 7s, 14s, 21s....
2" 0s, 8s, 16s, 24s,...
3: 0,11,22, 33s,...
4: 0, 12, 24,36,48s,...
LCM of 7s , 8s ,11s ,12 is : 7 * 2 *2*2 *11 * 3 = 1848 sec = 30 min and 48 seconds.
so we add 30 m 48 sec to the previous time instant that they tolled together.
next time all the bells will toll together will be at 9 h 30min 48 sec
next time it will be 10 h 1 min 36 sec
next it will be at 10 h 32 min 24 sec
next it will be at 11 h 3 min 12 sec
next it will be at 11 h 34 min 0 sec
next it will be at 12 h 04 min 48 sec.. this is after 3 hrs from 9 am.
===> to do it simply: in 180 minutes = 3 hrs, they toll together
= 180 min / 30min 48sec times
= 5.84 times that is 5 times.
Hope it helps....