Aptitude - Problems on H.C.F and L.C.M - Discussion

I got lcm 2800 but here it is 1400. Please anyone explain this in detail.

I too agree, the answer is 3/5.

2/10, 25, 35, 40.

2/5, 25, 35, 20,
2/5, 25, 35, 10,
5/5, 25, 35, 5,
5/1, 5, 7, 1,
7/1, 1, 1, 1.

LCM = 2 * 2 * 2 * 5 * 5 * 7 = 1400.

I am not getting the answer. Please explain.

Hi. Isn't the answer 3/5?

How did it become 3/1400?

The number obtained by dividing 3 by 5 is greater than the number obtained by dividing 3 by 1400. Besides what is the credibility of the formula to find the hcf of a fraction? And also 3/5 can be used to divide all the four fractions in the question. If the question is to find the HCF of fractions then why can't the HCF we obtain, when used to divide the fractions in the question give us fractions rather than integers?

Agree @Sanidhya.

Please explain.

Agree @Sanidhya.

Can anyone explain us?

Why isn't the answer 3/5 as 3/5 divides all numbers and it is also higher than 3/1400?

What is the need for so much of calculations?

Since we know that HCF of any fraction is computed with the following formula = HCF of Numerators/LCM of denominators.

Now see the Options:

Numerators has to be less than the given numbers (9, 12, 18, 21) since, it is HCF. This rules out Options B and D. We are left with options A and C.

Now denominator is the LCM which shall be more than the given number i.e. 10, 25, 35, 40. Therefore Options C is the correct answer.

Thats long process, tell me short cut method.