CAT 2015 Quantitative Ability

Since the HCF of 24 and 56 is 8, the side of the identical square plots must be one of the factors of 8.
The factors of 8 are 1,2,4 and 8
If side of the square plot is 1 m, the length of fencing material required is
(25 × 56 + 57 × 24) = 2768 m
But 2768 m > 2700 m.
If side of the square plot is 2 m, the length of fencing material required is
(29 x 24 +13 x 56) = 1464 m < 2600 m
∴ For minimum fencing material to be left the side of identical square plot = 2m.