# Example 6 - Chapter 9 Class 8 Mensuration

Last updated at April 16, 2024 by Teachoo

Chapter 9 Class 8 Mensuration

Serial order wise

Last updated at April 16, 2024 by Teachoo

Example 6 In a building there are 24 cylindrical pillars. The radius of each pillar is 28 cm and height is 4 m. Find the total cost of painting the curved surface area of all pillars at the rate of Rs 8 perใ ๐ใ^2. Given, Height of each pillar = 4 cm & Radius of each pillar = 28 cm = 28/100 m To find cost of painting the pillars, We find Curved Surface area of pillars Curved Surface Area of Pillar Curved Surface Area = 2ฯrh = 2 ร 22/7 ร 28/100 ร 4 = 2 ร 22 ร 4/100 ร 4 = 44 ร 16 ร 1/100 = 704/100 m2 Now, there are 24 pillars So, Total Surface area to be painted = 24 ร Curved Surface Area of 1 pillar Total Surface area to be painted = 24 ร Curved Surface Area of 1 pillar = 24 ร 704/100 = 16896/100 = 168.96 m2 Now, Cost of painting is Rs 8 perใ ๐ใ^2 So, Cost of painting per 1 m2 = Rs 8 Cost of painting per 168.96 m2 = Rs 8 ร 168.96 = Rs 8 ร 16896/100 = Rs 135168/100 = Rs 1351.68