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.
Rasheed Tolulope said:
1 decade ago
@ Neem.
To find the LCM of 2,4,6,8,10, and 12 using Rasabtol Cross Method (RCM).
2 x 4 x 6 x 8 x 10 x 12 = 2 [1 x 2 x 3 x 4 x 5 x 6]
2 [1 x 3 x 5 x {2 ( 1 x 2 x 3)}]
Apply BODMAS rule,
= 2 [1 x3 x 5 x 2 x 6]
= 2 [1 x 2 x 5 x 3 (1x2)]
= 2 [1 x 2 x 5 x 3 (2)]
= 2 [60]
= 120.
Hence, the LCM = 120
To find the LCM of 2,4,6,8,10, and 12 using Rasabtol Cross Method (RCM).
2 x 4 x 6 x 8 x 10 x 12 = 2 [1 x 2 x 3 x 4 x 5 x 6]
2 [1 x 3 x 5 x {2 ( 1 x 2 x 3)}]
Apply BODMAS rule,
= 2 [1 x3 x 5 x 2 x 6]
= 2 [1 x 2 x 5 x 3 (1x2)]
= 2 [1 x 2 x 5 x 3 (2)]
= 2 [60]
= 120.
Hence, the LCM = 120
Shanthi priya said:
1 year ago
Six bells commence tolling together at intervals of 2, 4, 6, 8, 10, and 12 seconds respectively. In 30 minutes, they toll together 16 times.
The concept used is Least common multiplication. But we have to add 1 because at the start all bells will be rung once a time after they ring 15.
The concept used is Least common multiplication. But we have to add 1 because at the start all bells will be rung once a time after they ring 15.
(29)
Sairam said:
7 years ago
One doubt. Let's take all the bells are tolling together. There are two questions. First question how many tolls from 7 to 7:30 and the second question being g 7:30 to 8. One bell tolls at 7:30. Should we count it on the first case or the second case?
Can anyone solve this?
Can anyone solve this?
Sunil said:
7 years ago
Just remember easily.
2,4,6,8,10,12.....take LCM, we get 120.
What they asking how many time toll together in 30 minutes
30minutes convert to seconds.
30*60=1800sec.
We have derived : 1800 ÷ 120=15.
At the time of zeroth sec tolls is 1 add total count 15+1=16.
2,4,6,8,10,12.....take LCM, we get 120.
What they asking how many time toll together in 30 minutes
30minutes convert to seconds.
30*60=1800sec.
We have derived : 1800 ÷ 120=15.
At the time of zeroth sec tolls is 1 add total count 15+1=16.
Y Anush said:
11 months ago
Six bells commence tolling together and toll at intervals of 2, 4, 6, 8 10 and 12 seconds respectively.
Here all the bells commence toll together i.e. they all rang at 0th second, and from then they rang 15 times. So, we added 15+1 = 16.
Here all the bells commence toll together i.e. they all rang at 0th second, and from then they rang 15 times. So, we added 15+1 = 16.
(23)
Nand said:
9 years ago
Can anyone please help me out getting the answer of the below question.
The bells commence tolling together & they toll after 0.25, 0.1 & 0.125 seconds. After what interval will they again toll together?
The bells commence tolling together & they toll after 0.25, 0.1 & 0.125 seconds. After what interval will they again toll together?
Yunus said:
1 decade ago
One is add because it is clearly given in the question that.
"Six bells commence tolling together" that means all bells rang once than after that rang in intervals of 2 4 6 8 10 and 12.
So add 1 to answer.
"Six bells commence tolling together" that means all bells rang once than after that rang in intervals of 2 4 6 8 10 and 12.
So add 1 to answer.
Devi said:
2 years ago
First we took;
2,4,6,8,10 in L.C.M.
After that, we have 120 seconds
Here, it's said 30minutes,
So, 1min = 60second,,
2min = 120second,
So,
We divide 30รท2 = 15.
At Starting stage one time rang 15+1=16.
2,4,6,8,10 in L.C.M.
After that, we have 120 seconds
Here, it's said 30minutes,
So, 1min = 60second,,
2min = 120second,
So,
We divide 30รท2 = 15.
At Starting stage one time rang 15+1=16.
(132)
Dilip said:
5 years ago
See why 1 added here means, it is mentioned in the question that "six bells tolling together and tolls " already tolled at starting and tolling after in intervals.
Hope you all understand.
Hope you all understand.
(19)
Dushanthi said:
1 decade ago
Why we find the L.C.M.?
I can't understand the L.C.M. method. What is the difference between L.C.M and H.C.M. Why didn't use the H.C.M. method in here. Please anyone can explain me.
I can't understand the L.C.M. method. What is the difference between L.C.M and H.C.M. Why didn't use the H.C.M. method in here. Please anyone can explain me.
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