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 5.50 per m².​

Answer 1

Given :

Length of cubical box with lid = 30cm

To Find :

Cost of painting the inside and outside of the box at Rs 5.50 per m²

Solution :

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

Surface area of the cube = 6a²

=> 6 x 30 x 30

=> 5400 cm²

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

So, Total surface area of cube = Inner surface area + outer surface area

=> 5400 + 5400

=> 10800 cm²

Converting cm² into m²

Surface area in m² = 10800/10000

Surface area in m² = 1.08 m²

Cost of painting the cubical box = Rs. 5.50 m²

Total cost of painting = 5.5 × 1.08

Total cost = Rs. 5.94

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

Answer 2

A N S W E R :

• The total cost of painting the cubical box from outside and inside is Rs. 5.94

Given :

• A cubical box with lid has a length of 30 cm

To find :

• Find the total cost of painting the inside and outside of the box at 5.50 per m² ?

Solution :

• 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 pr sq m

=> Total cost of painting = 5.50 × 1.08

=> Total cost of painting = Rs. 5.94

Hence,

• The total cost of painting the cubical box from outside and inside is Rs. 5.94