SSC CGL 2019 PYQ — Question 71

SSC CGL - 4th June 2019 - Shift 1 • Quantitative Aptitude • Q71

A solid cube of volume 13824 cm3 is cut into 8 cubes of equal volumes. The ratio of the surface area of the original cube to the sum of the surface areas of three of the smaller cubes is:

Show answer & explanation

Correct answer: C

Explanation

Correct answer is option 3 i.e. 4 : 3

Concept

Understanding

Application

Volume of cube = side3

Surface area = 6 × side2

Volume of big cube = 13824 cm3 (This data is not required)

Let the volume of the big cube is 8x3

So,

Side of big cube = 2x

 

 

Volume of each small cube = 1x3

Side of each small cube = 1x

Surface area of big cube = 6 × 2x × 2x = 24x2

Surface area of each small cube = 6x2

Surface areas of three of the smaller cubes = 18x2

Required ratio = 24x2 : (3 × 6x2) = 4 : 3