UPSC CAPF Assistant Commandant Model Paper 3

GIVEN:
2 similar cubes are placed adjacent to each other such that the total surface area of the structure is 2890 cm2
CONCEPT:
Number of edges in the cube = 12
Total surface area of the structure (2 similar cubes are placed adjacent to each other) = 10 × (side) ‌2
Note:Total surface area of 1 cube = 6a2 .When 2 cubes are kept adjacent to each other then 2 common surfaces will come inside the structure and resultant total surface area = 6 + 6 – 2 = 10.
CALCULATION:

10×(side)2=2890
⇒(side)2=289
⇒ Side = 17 cm
Since the cube has 12 edges each equal to the side of the cube.
∴ Total length of all the edges of a cube = 17 × 12 = 204 cm