Question

Find the ratio of surface area of a cuboid to the volume if the length is 2 times of breadth which is 2 times of height which is 2 cm.

• A. 7: 2
• B. 7: 4
• C. 3 : 2
• D. 3 : 4

Answer 1

The correct option is D

3 : 4

Let's read the question from backwards.

Height is 2 cm.
Therefore breadth would be 4 cm(2 times the height) and the length would be 8 cm(2 times the breadth).

$l=8cm,b=4cm,h=2cm$

$\text{Surface area}=2(lb+bh+hl)=2(8\times 4+4\times 2+2\times 8)=112c{m}^2$

$\text{Volume}=lbh=8\times 4\times 2=64c{m}^3$

$\text{Required ratio}=\frac{\text{surface area}}{\text{volume}}=\frac{112}{64}=\frac{7}{4}$
Hence, the required ratio is 7:4.