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. 15)
15.
A, B and C start at the same time in the same direction to run around a circular stadium. A completes a round in 252 seconds, B in 308 seconds and c in 198 seconds, all starting at the same point. After what time will they again at the starting point ?
Answer: Option
Explanation:
L.C.M. of 252, 308 and 198 = 2772.
So, A, B and C will again meet at the starting point in 2772 sec. i.e., 46 min. 12 sec.
Discussion:
66 comments Page 6 of 7.
Preeti said:
1 decade ago
Why we are taking LCM in this question?
Atul Khanna. said:
1 decade ago
Anyone can you explain what is the total number of revolutions of each of them in above question?
Karthi said:
1 decade ago
First note down in question, if they ask multiple number or factors.
Factors - denominators -solve hcf.
Multiple - numerators in fraction- solve lcm.
Factors - denominators -solve hcf.
Multiple - numerators in fraction- solve lcm.
Rekha said:
1 decade ago
@Rehana.
Could you please explain when you took LCM of 63 77 99 with 7, how did it come out to be 9 11 9 (third step).
Could you please explain when you took LCM of 63 77 99 with 7, how did it come out to be 9 11 9 (third step).
Isa said:
1 decade ago
252 = 2x2x3x3x7
308 = 2x2x7x11
198 = 2x3x3x11
L.C.M. of the given numbers = product of all the prime factors of each of the given number with greatest index of common prime factors, so
2x2x3x3x7x11 = 2272
308 = 2x2x7x11
198 = 2x3x3x11
L.C.M. of the given numbers = product of all the prime factors of each of the given number with greatest index of common prime factors, so
2x2x3x3x7x11 = 2272
Rehana said:
1 decade ago
2/ 252 308 198=126 154 99
2/ 126 154 99= 63 77 99
7/ 63 77 99
11/ 9 11 9
9/ 9 1 9 = 1 1 1
2/ 126 154 99= 63 77 99
7/ 63 77 99
11/ 9 11 9
9/ 9 1 9 = 1 1 1
Rahul said:
1 decade ago
How the lcm 2772 came ? when I calculated it is big enough than 2772. Please explain me.
Anish said:
1 decade ago
Why do you take LCM?
Parveen Kumar said:
1 decade ago
How do we decide that we calculate LCM or HCM?
Ramya said:
1 decade ago
Can anyone tell me how to take quick L. C. M for big numbers? please.
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