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 2 of 7.
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
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
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).
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.
Atul Khanna. said:
1 decade ago
Anyone can you explain what is the total number of revolutions of each of them in above question?
Preeti said:
1 decade ago
Why we are taking LCM in this question?
NaveenKK said:
1 decade ago
How we can get quick idea LCM as answer at exam time?
Ghanshyam said:
1 decade ago
And how to calculate HCF? Please tell me this answer also.
Senthil said:
1 decade ago
What is the need to take L.C.M in this question?
Akshay said:
1 decade ago
Here every one should be at the same time according to question.
But after completion of 1 round not before it.
So each individual have to complete the round. That's why we have to consider their full time that's the reason to take LCM.
But after completion of 1 round not before it.
So each individual have to complete the round. That's why we have to consider their full time that's the reason to take LCM.
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