Question

A closed box made of wood of uniform thickness has length, breadth and height as $12cm,10cm$ and $8cm$, respectively. If the thickness of the wood is $1cm$, the inner surface area is

• A. $456c{m}^2$
• B. $376c{m}^2$
• C. $264c{m}^2$
• D. $696c{m}^2$

Answer 1

Answer: (B)

$376c{m}^2$

Internal dimensions of the box are :
Length $=(12-2)cm=10cm$
Breadth $=(10-2)cm=8cm$
Height $=(8-2)=6cm$
$\therefore$ Inner surface area $=2\times (10\times 8+8\times 6+6\times 10)c{m}^2$
$=2\times (80+48+60)c{m}^2$
$=2\times 188c{m}^2$
$=376c{m}^2$