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:
171 comments Page 9 of 18.
Gowthami said:
1 decade ago
As they all together, why should we add 1, I couldn't understand. Why will first bell toll first, it starts together with the 5 bells know?
Akhil said:
1 decade ago
4 bells ring at an interval of 12, 16, 20, 24 min if they start together at 9 am after how long will they ring together.
Sam said:
1 decade ago
12 = 2*2*3.
16 = 2*2*2*2.
20 = 2*2*5.
24 = 3*2*2*2.
L.C.M = 2*2*2*2*3*5 = 240 min.
= 240 min/60 min = 4 hr.
So at 1 pm it will ring again (9+4).
16 = 2*2*2*2.
20 = 2*2*5.
24 = 3*2*2*2.
L.C.M = 2*2*2*2*3*5 = 240 min.
= 240 min/60 min = 4 hr.
So at 1 pm it will ring again (9+4).
Anand jannu said:
1 decade ago
@Saravan explained excellent. But that concept 30/2+1 I didn't understand. But I follow concept said by @Saravan.
Awanish said:
10 years ago
I am not agree with this explanation 1st beep at 0 sec so time start after 0 so within 30 min it beeps 15 times.
For 16 beep it takes 30 min 1 sec.
For 16 beep it takes 30 min 1 sec.
Renuka said:
10 years ago
Really it is a good explanation. Thanks.
Secotad said:
10 years ago
The bells toll at Intervals of 10mins, 15mins, 20mins. If they toll together at 11:00am, when next do they toll again.
Secotad said:
10 years ago
The bells toll at Intervals of 10mins, 15mins, 20mins. If they toll together at 11:00am, when next do they toll again.
Muneesh said:
10 years ago
Formula: (n/2+1) from n--30.
= 30/2+1 = 16 answer.
= 30/2+1 = 16 answer.
Dhivakar said:
10 years ago
If all the bells starts to toll, it will get the toll together only at the 120th second. If a bell starts to tell, will it start from zero or directly from 120?
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