Question

The internal measures of a cuboidal room are 10 m x 8 m x 4m. Find the total cost of white washing all four walls of a room, if the cost of white washing is ` 10 per m2

Answer 1

the internal measures of a cuboid room are 10m x

Answer 2

★ Given:

Length of the room = 10 m

Breadth of the room = 8 m

Height of the room = 4 m

Cost of white washing 1 m² = Rs. 10

★ To Find:

The total cost of white washing the 4 walls.

★ Analysis:

In this question, we will have to find the LSA of a cuboid and then multiply the LSA with the rate of 1 m².

★ Formulae to use:

→ $\sf{\boxed{LSA\:of\:Cuboid=2(lh+bh)}}$

★ Solution:

Length = 10 m

Breadth = 8 m

Height = 4 m

LSA of cuboid = 2 (lh + bh)

= 2 x [(10x4) + (8x4)]

= 2 x [40 + 32]

= 2 x 72

= 144 m²

Hence the LSA of the cuboid is 144 m².

Cost of whitewashing 1 m² = Rs 10.

Cost of whitewashing 144 m² = 144 x 10

= Rs 1440

Hence the cost of whitewashing the four walls of the room is Rs. 1440.

Knowledge Bytes:

→ Formulae Related to Cuboid

✳ LSA = 2 (lh + bh)

✳ TSA = 2 (lh + bh + lb)

✳ Volume = lbh

✳ To find area of 4 walls and ceiling = 2 (lh+ bh) + lb