Question

The external length, breadth and height of a closed box are 18cm, 21cm and 15cm respectively. The total inner surface area of the box is 1518 Sq. Cm. If the walls of the box are of uniform thickness t cm, then find t ?

Answer 1

Answer:

Dimension of a closed rectangular wooden box are 18cm,10cm and 6cm, respectively.

The thickness of wood is

2

1

cm

∴ Volume of rectangular wooden block =18×10×6=1080cm

3

And, volume of hollow space in rectangular wooden block =17×9×5=765cm

3

∴ Volume of rectangular wood =(1080−765)cm

3

=365cm

3

Now, weight of empty box =15kg

∴ Weight of a cubic cm of wood =

365

15

=

21

1

kg

Weight of box filled with sand =100kg

Weight of sand =(100−15)kg=85kg

∴ Weight of a cubic cm of sand =

765

85

kg=

9

1

kg