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 3 of 7.
Arvind Kumar said:
8 years ago
Whenever we need to find a number which will get divisible by certain numbers completely we take lcm. On the other case, if we need to find the number which will divide certain numbers completely we take HCf.
Here in case, we need to find the number which gets completely divide by 252, 308 & 198 that is why we are calculating LCM.
Here in case, we need to find the number which gets completely divide by 252, 308 & 198 that is why we are calculating LCM.
(1)
Akshat said:
8 years ago
Very helpful, Thank you all.
Greeshma said:
8 years ago
We take lcm because the point of time they meet, will be exactly divisible by their individual timings. 2772 is the smallest number divisible(that is when they first meet).
That is their lcm.
2772/60= 46.2 mints.
.2 mints = 12 seconds (.2*60).
So, the answer is 46 minutes 12 seconds.
That is their lcm.
2772/60= 46.2 mints.
.2 mints = 12 seconds (.2*60).
So, the answer is 46 minutes 12 seconds.
Shyam hyd said:
8 years ago
@JOTHI
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 * 2 * 7 * 9 * 11 = 2772.
2772 sec. i.e., 46 min. 12 sec.
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 * 2 * 7 * 9 * 11 = 2772.
2772 sec. i.e., 46 min. 12 sec.
Anisha said:
8 years ago
When to take lcm and when the hcf? Please explain it clear.
Jothi said:
8 years ago
Why we take LCM for this problem? How to understand. Anyone please tell me.
Vijay said:
8 years ago
2772/60 = 46 min and remaining 12 sec.
or
2772/60=>693/15=>231/5 = 46 min 1/5.
1/5 =1 * 60/5 = 12 sec.
46 min 12 sec.
or
2772/60=>693/15=>231/5 = 46 min 1/5.
1/5 =1 * 60/5 = 12 sec.
46 min 12 sec.
Sandy said:
8 years ago
2400 sec= 40min and 360 sec = 6 min. Remaining 12 sec (2400+360+12).
Deepak said:
8 years ago
The Right answer is 46 minutes and 20 seconds, this is a correct solution which I am going to explain below:
Lcm of (252,308,198) is 2772 seconds.
Converting in minutes by dividing 60,
2772/60 = 46 minutes and 20 seconds.
Lcm of (252,308,198) is 2772 seconds.
Converting in minutes by dividing 60,
2772/60 = 46 minutes and 20 seconds.
Prahlad said:
8 years ago
2772 /60 =924/20 = 46minutes 4 seconds.
But 2772 /60 = 46minutes 12 seconds.
But 2772 /60 = 46minutes 12 seconds.
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