Example 5 - The internal measures of a cuboidal room are 12 m x 8 m

Example 5 - Chapter 11 Class 8 Mensuration - Part 2
Example 5 - Chapter 11 Class 8 Mensuration - Part 3 Example 5 - Chapter 11 Class 8 Mensuration - Part 4 Example 5 - Chapter 11 Class 8 Mensuration - Part 5

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Example 5 The internal measures of a cuboidal room are 12 m × 8 m × 4 m. Find the total cost of whitewashing all four walls of a room, if the cost of white washing is Rs 5 per 𝑚^2. What will be the cost of white washing if the ceiling of the room is also whitewashed. Given, Length of room = 𝑙 = 15 m Breadth of room = 𝑏 = 10 m & Height of room = ℎ = 7 m To find cost of whitewashing, first we find area to be whitewashed Finding Area to be whitewashed Given that 4 walls and ceiling is whitewashed So, Area Painted = Area of 4 walls + Area of top ceiling Area of 4 walls Area of 4 walls = 2ℎ(𝑙+𝑏) = 2×4×(12+8) = 2×4×20 = 160 m2 Area of ceiling Area = Length × Breadth = 12 × 8 = 96 m2 Thus, Area of 4 walls = 160 m2 Area of 4 walls + Area of ceiling = 160 + 96 = 256 m2 Now, we need to cost of painting the 4 walls, and also the cost of painting the walls + Ceiling Cost of painting the 4 walls Given that Cost of white washing is Rs 5 per m2 So, Cost of white washing 1 m2 = Rs 5 Cost of whitewashing 160 m2 = Rs 5 × 160 = Rs 800 So, Rs 800 is required to paint the 4 walls Cost of painting the 4 walls + Ceiling Cost of white washing 1 m2 = Rs 5 Cost of whitewashing 256 m2 = Rs 5 × 256 = Rs 1280 So, Rs 1280 is required to paint the 4 walls + Ceiling

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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.