Question

A closed box measures 66 cm, 36 cm and 21 cm from outside. If its walls are made of metal-sheet, 0.5 cm thick, then find the weight of the box, if $1c{m}^3$ of metal weighs 3.6 g.

• A. 17985.6 g
• B. 15725.6 g
• C. 13625.6 g
• D. 15825.6 g

Answer 1

The correct option is D 15825.6 g

Given,
The external dimensions of a closed wooden box are $66cm,36cm$ and $21cm$ respectively.
As the thickness is $0.5cm$ , the internal length, breadth and height of the closed box are $66-2\left(0.5\right)=65cm,36-2\left(0.5\right)=35cm$ and $21-2\left(0.5\right)=20cm$, respectively.
Now, volume of wood used to make the box $=$ Volume with the external dimensions $-$ Volume with the internal dimensions
=> Volume of wood used to make the box $=(66\times 36\times 21)-(65\times 35\times 20)=49896-45500=4396cucm$

So, weight of the wood $=3.60\times 4396=15825.6g$