Question

A cuboid is formed by joining three cubes with sides of 2 cm each. The ratio of the surface area of the resulting cuboid to the total surface area of the three cubes is

• A. 7:9
• B. 9:7
• C. 2:6

Answer 1

The correct option is A 7:9

The dimensions of the resulting cuboid are:

length = 6 cm, breadth = 2 cm, height = 2 cm

∴ Surface area of the cuboid $=2(6\times 2+2\times 2+6\times 2)c{m}^2$
$=2\times 28c{m}^2$
$=56c{m}^2$

Surface area of the three cubes $=3\times 6\times (2{)}^{2}c{m}^2$
$=72c{m}^2$

∴ Required ratio = 56:72 = 14:18 = 7:9