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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:
172 comments Page 7 of 18.
NIDISH said:   9 years ago
If 6 bells takes 6 seconds then how much seconds does the 10 bells take? can anyone solve this?
Anjil said:   2 weeks ago
@All.

If the bells didn't ring together, would we still add 1. Anyone, please explain to me.
Prem said:   1 decade ago
I am unable to understand why we are using lcm method for this problem. Can anyone explain?
Bahhep said:   10 years ago
In 30th min they meet together but they don't toil together. So it should be 15 not 16.
Avinash said:   6 years ago
@Shahrukh.

Here, it is mentioned that the bell starts after tolling thas why we add 1.
Prasanth v said:   8 years ago
30/2=15.

And 15+1=16 (added +1 reason is first 0 to 2 sec bell is tolled at a time).
Ashish said:   2 decades ago
Forget about 30/2, look at the answer given by Sravan. 1800/120=15

Thanks Sravan.
Neem said:   1 decade ago
Can you please tell me how to calculate LCM of above series no. ? Please tell me.
Bhavadip Gothadiya said:   8 years ago
Anyone explain to me, why to add additional 1?

Why (30/2) +1 instead of (30/2)?
Rahul said:   8 years ago
Total 30 mins 1800 secs.

Coincide at 120 sec.
Divided the 1800/120=15+1=16.
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