Four bells begin to ring together and they ring after an interval of 6,8,9 and 12 second respectively. How many times will they ring together in one hour, including the one at the start?	Choose the correct choice.
A) 50	B) 56	C) 62	D) 51	E) 55
LCM is 72. So they ring together in every 72 sec.   there are 3600 sec in 1 hr. so, 3600/72=50.   and 1 ring at the beginning. makes it 51.   ANSWER:51
<result>D</result>
Four bells begin to ring together and they ring after an interval of 6,8,9 and 12 second respectively. How many times will they ring together in one hour, including the one at the start?