Question

9. The four walls of an auditorium of dimensions 18.4 m x 12.6 mx 11.5 m have
to be painted. Find the cost of painting at the rate of 38 per sq. m.​

Answer 1

Answer:

first, take out the lateral surface area also known as area of four walls

formula- 2(length+breadth)×height

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Step-by-step explanation:

length = 18.4m

breadth = 12.6m

height = 11.5m

lateral surface area = 2×(length+breadth)×height

= 2×(18.4+12.6)×11.5

= 2×31×11.5

= 713 sq.m

rate of painting=38/sq.m

total cost = rate×lateral surface area

= 38×713

= ₹27,094 (ans)

Answer 2

Given :

• Dimensions of the four walls of an auditorium = 18.4 m × 12.6 m × 11.5 m

• The cost of painting per m² = Rs. 38

To find :

• Cost of painting the four walls

According to the question,

We know,

• Lateral surface of cuboid = 2(l + b) × h

Where,

• l = Length
• b = Breadth
• h = Height

➞ Lateral surface area of cuboid = 2(l + b) × h

➞ Lateral surface of cuboid = 2(18.4 m + 12.6 m) × 11.5 m

➞ Lateral surface area of cuboid = 2(31 m) × 11.5 m

➞ Lateral surface area of cuboid = 2(356.5) m²

➞ Lateral surface area of cuboid = 713 m²

• So, the lateral surface area of cuboid is 713 m².

Now,

➞ Cost of painting = Rs. 38 × 713

➞ Cost of painting = Rs 27,093

• So, the cost of painting the four walls is Rs. 27,094.