Question

The outer length breadth and height of a box open at the top are 10 dm, 8 dm, and 5 dm respectively If the thickness of the wood is 1 dm then the inner surface area of the box is

• A. $248$ $d{m}^2$
• B. $452$ $d{m}^2$
• C. $451$ $d{m}^2$
• D. $483$ $d{m}^2$

Answer 1

The correct option is A $248$ $d{m}^2$

External dimensions of the wooden box :

length = $12dm$

breadth = $6dm$

height = $8dm$

thickness of the wooden box = $1dm$

Inner dimensions of the wooden box :

$l=12-1-1=12-2=10dm$

$b=6-1-1=6-2=4dm$

$h=8-1-1=8-2=6dm$

Hence, the inner surface area of the wooden box

$=2(lb+bh+hl)$

$=2(10\times 4+4\times 6+6\times 10)$

$=2(40+24+60)$

$=2\left(124\right)$

$=248sq.dm$