Question

The length, breadth and height of a room are 5 m, 4 m and 3 m respectively. Find the
cost of white washing the walls of the room and the ceiling at the rate of
Rs 7.50 per m2​

Answer 1

Answer:

here it means that at the length of 5 metre there are two walls with the height of of 3 metre and two walls of 4 metre length and 3 metre height.

area of the 1 wall with the length 5 metre = 5×3 = 15m²

area of two walls with the length 5 metre = 15 × 2 = 30m²

area of 1 wall with the length 4 metre = 4 × 3 = 12m²

area of 2 wall with the length 4 metre = 12 × 2 = 24m²

total area of all the walls = (30+24)m² = 54m²

length of ceiling = 5m

breadth of ceiing = 4m

area of ceiling = 20m

total area of walls and ceiling = (54+20)m² = 74m²

cost of painting per metre² = 7.50

cost of painting 74m² = 555

Answer 2

Question ::-

The length, breadth and height of a room are 5 m, 4 m and 3 m, respectively. Find the cost of white washing the walls of the room and the ceiling at the rate of ₹17.50 per ${m}^{2}$

Given ::-

• Length of room = 5m

• Breadth of room = 4m

• Height of room = 3m

• Cost of White washing per ${m}^{2}$ = Rs. 7.50

To find ::-

• cost of white washing the walls of the room and the ceiling at the rate of Rs 7.50 per ${m}^{2}$ ?

Solution ::-

The room is like a cuboid whose four walls (lateral surface) and ceiling are to be white washed.

∴ Area for white washing

= [Lateral surface area] + [Area of the ceiling]

= [2(l + b)h] + [l x b]

= [2(5 + 4) x 3] ${m}^{2}$ + [5 x 4] ${m}^{2}$

= 54 ${m}^{2}$ + 20 ${m}^{2}$

= 74${m}^{2}$

_____________

Cost of white washing for 1 ${m}^{2}$ area

= Rs. 7.50

∴ Cost of white washing for 74 ${m}^{2}$ area

= Rs. (7.50 x 74)

= Rs. 555

Thus, the required cost of white washing = Rs. 555