Question

The internal length, breadth and height of a closed box are 1 m, 80 cm and 25 cm respectively. If its sides are made of 2.5 cm thick wood, then find the volume of wood used to make the box.

• A. $0.02475m^3$
• B. $0.06775m^3$
• C. $0.03975m^3$
• D. $0.07525m^3$

Answer 1

The correct option is B $0.06775m^3$

Given,
The internal length, breadth and height of a closed box are $1m=100cm,80cm$ and $25cm$ respectively.
As its sides are made of $2.5cm$ , the external length, breadth and height of the closed box are $100+2\left(2.5\right)=105cm,80+2\left(2.5\right)=85cm$ and $25+2\left(2.5\right)=30cm$ 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 $=(105\times 85\times 30)-(100\times 80\times 25)=267750-200000=67750cucm=0.06775m^3$