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Aptitude - Problems on H.C.F and L.C.M - Discussion

Discussion Forum : Problems on H.C.F and L.C.M - General Questions (Q.No. 3)
Problems on H.C.F and L.C.M
3.
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 ?
4
10
15
16
Answer: Option
Explanation:

L.C.M. of 2, 4, 6, 8, 10, 12 is 120.

So, the bells will toll together after every 120 seconds(2 minutes).

In 30 minutes, they will toll together 30 + 1 = 16 times.
2

Discussion:
171 comments Page 13 of 18.
Pardeep said:   8 years ago
I am not able to understand it. Why one is added at the last step?
Oyinda said:   8 years ago
Why is 1 added to 15 in the last step?
Roxanne Santiago said:   8 years ago
Thanks for the explanation. It cleared my doubt.
Sapana said:   8 years ago
How to calculate 120?
Abhishek pandey said:   8 years ago
According to me, the answer is 15.
NIDISH said:   8 years ago
If 6 bells takes 6 seconds then how much seconds does the 10 bells take? can anyone solve this?
Ramya said:   8 years ago
Excellent explanation @Sravanreddy.
Vishnu said:   8 years ago
Answer 15 is right.

The reason is we can't consider 0th sec bell together like in clock problem hour and min. Hand coincide 11 times in 12 hours.
Chandan said:   8 years ago
Thanks for the great explanation @Sravanreddypailla.
Harshini pusarla said:   8 years ago
Why 1 is added?
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