Question

If length, breadth and height of a cuboid are increased by 20%, what is the percentage increase in the the total surface area of cuboid?

• A. $20\%$
  
• B. $22\%$
  
• C. $44\%$
  
• D. $40\%$
  

Answer 1

The correct option is C

$44\%$

Let $l,b,h$ be the original dimensions
New dimensions
$=\left(1.2l\right),\left(1.2b\right),\left(1.2h\right)$

Orignal total surface area
$=2(lb+bh+hl)$

New total surface area
$=2(1.44lb+1.44bh+1.44hl)$
$=1.44\times 2(lb+bh+lh)$
$\Rightarrow 44\%$ increase in the total surface area.