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)
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 ?
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:
170 comments Page 3 of 17.
Ashu said:
5 years ago
How to find LCM for this? Please tell someone.
Avinash said:
5 years ago
@Shahrukh.
Here, it is mentioned that the bell starts after tolling thas why we add 1.
Here, it is mentioned that the bell starts after tolling thas why we add 1.
Sirichandana said:
5 years ago
Very well said, thanks @Sravan.
Shahrukh said:
6 years ago
Why is 1 being added? How can at 0 sec they toll together? So why adding 1? When 1st toll is after 2 min then at 30th min they will toll 15th time. Thats it.
Raksha said:
6 years ago
Why 1 is added please explain?
Surajbhan singh said:
6 years ago
Why 1 is added your answer in the question. Read it once again carefully.
(1)
Michael said:
6 years ago
Why 1 is added? Explain it.
Chojoy said:
6 years ago
You can also use AP(Arithmetic Progression) method to solve this problem.
Since the given tolling interval are in AP,ie 2 4 6 8 10 12........ , and nth time is 30min.
HENCE, using AP formula, we have;
T(N)=a+(n-1)d
a=2, d=4-2 ie d=2, n=?
30=2+(n-1)2
30=2+2n-2
ie, 30=2n
therefore, n=15.
Since we have to consider first toll, add+1 to n.
Therefore, the answer is 15+1=16.
Since the given tolling interval are in AP,ie 2 4 6 8 10 12........ , and nth time is 30min.
HENCE, using AP formula, we have;
T(N)=a+(n-1)d
a=2, d=4-2 ie d=2, n=?
30=2+(n-1)2
30=2+2n-2
ie, 30=2n
therefore, n=15.
Since we have to consider first toll, add+1 to n.
Therefore, the answer is 15+1=16.
(2)
Adithya said:
6 years ago
Thank you @Sundar.
ASHNA said:
6 years ago
Thanks @Saravan and @Deepak.
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