Four bells commence tolling together and toll at intervals of 2, 3, 4 and 5 seconds respectively. In 10 minutes, how many times do they toll together ?
Choose the correct choice from the following choices:
A) 10
B) 11
C) 12
D) 13
E) 14
LCM of 2, 3, 4, and 5 is 60.   So, after each 60 seconds, they would toll together.   Hence, in 10 minutes, they would toll 10*60 seconds / 60 seconds = 10 times   But then the question says they commence tolling together. So, they basically also toll at thebeginning(0second).   So, total tolls together = 10+1= 
<gadget id="calculator">10+1</gadget>
<output>11</output>
11   Answer: 11
<result>B</result>
Four bells commence tolling together and toll at intervals of 2, 3, 4 and 5 seconds respectively. In 10 minutes, how many times do they toll together ?