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

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.

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