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 ?
A. 4
B. 10
C. 15
D. 16
Answer: Option D
Solution (By Examveda Team)
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
$$\frac{{30}}{2}$$ + 1 = 16 times
This Question Belongs to Arithmetic Ability >> Problems On H.C.F And L.C.M
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Comments (9)
Related Questions on Problems on H.C.F and L.C.M
Why adding +1
why did we add 1
why adding plus 1
in six bell=2,4,6,8,10,12.,if we count the digit of all given no.=6,
so answer should be the vice versa of question ,means
so in 30 min tolling of bell like,0,2,4,6,8,10,12,14,16,18,20,22,24,26,28,30.
total no of digit =16,
so ans =16.
note=counting should be starting from the 0.
But,if it start at 1 i.e last time they toll together at 11,then it should be 1,3,5,7,9,11,13,15,17,19,21,23,25,27 and 30
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
They all missed their 24
2,4,6,8,10,12 lcm is 120
1min=60 sec
120 sec= 2 min
.: ever 2 mins one bell
30 mins
0,2,4,6,8,10,12,14,16,18,20,22,26,28,30
Count all series =16 time
Ans-C
I don't understand how 16 times they will toll together. According to me the answer should be 15 times.