Examples

Chapter 11 Class 8 Mensuration
Serial order wise

This video is only available for Teachoo black users

This video is only available for Teachoo black users

Get live Maths 1-on-1 Classs - Class 6 to 12

### Transcript

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 peră€– đť‘šă€—^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 = 2Ď€rh = 2 Ă— 22/7 Ă— 28/100 Ă— 4 = 2 Ă— 22 Ă— 4/100 Ă— 4 = 44 Ă— 16 Ă— 1/100 = 704/100 m2 Now, there are 24 pillars So, Total Surface area to be painted = 24 Ă— Curved Surface Area of 1 pillar Total Surface area to be painted = 24 Ă— Curved Surface Area of 1 pillar = 24 Ă— 704/100 = 16896/100 = 168.96 m2 Now, Cost of painting is Rs 8 peră€– đť‘šă€—^2 So, Cost of painting per 1 m2 = Rs 8 Cost of painting per 168.96 m2 = Rs 8 Ă— 168.96 = Rs 8 Ă— 16896/100 = Rs 135168/100 = Rs 1351.68

Made by

#### Davneet Singh

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.