CMAT 2018 Solved Question Paper

The cube formed by joining 125 cubes will have each side equal to 5 units (let each cube has side of 1 unit]
∴ Volume of larger cube = 53 = 125 cu units
Now, in order to cover the larger cube completely.
The side of new cube must be 7 units.
∴ Volume of cube which will cover the larger cube = 73 = 343 cu units
Hence, required number of small cubes = 343-125 = 218