Aptitude

Question

Six bells commence tolling together and toll at intervals of 2, 4, 6, 8 10 and 12 seconds respectively. In 30 minutes, how many times do they toll together ?

i am getting 15 but answer given 16

L.cm of all is 120 , the bells will toll together after every 120 seconds(2 minutes).

In 30 minutes, they will toll together  30/2

Comments

Six bells commence tolling together

Which means if our counter starts at 12:00 then all will ring together at 12:00, then 12:02,12:04,12:06,....12:30

i.e. 0 to 30 with interval of 2 which means 16 times..

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@minipanda i am not getting why u have said--- then all will ring together at 12:00

at current time why they will toll

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Since its said that the bells commence ("start" to toll together). So just when we begin our 30mins countdown, they toll together i.e. at 0th sec...

 

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@ Prince Sindhiya method is correct. you just missed that all bells tolled at beggining.

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ok bro thnxxx :)