Question

A cubical box with lid has a length of 30 cm .Find the cost of painting the inside and outside of the box at rs 5.50 per m sq.

Answer 1

We have to find the surface area of the cubical box.

Surface area of the cube = 6a²  where a = 30 cm

⇒ 6*30*30

⇒ 5400 sq cm

As the cubical box has to be painted both from the outside and inside. 

So, the total surface area = Inner surface area + outer surface area

⇒ 5400 + 5400 

= 10800 sq cm

As we know that 1 sq m = 10000 sq cm

Surface area in sq m = 10800/10000

Surface area in sq m = 1.08 sq m

Cost of painting the cubical box = Rs. 5.50 per sq m

Total cost of painting = 5.5*1.08

Total cost = Rs. 5.94

So, the total cost of painting the cubical box from outside and inside is Rs. 5.94