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Learn in your speed, with individual attention - Teachoo Maths 1-on-1 Class


Transcript

Ex 9.2, 8 Find the cost of polishing a circular table-top of diameter 1.6 m, if the rate of polishing is Rs 15/m2. (Take π = 3.14) Here, Area to be polished = Area of circular table top Diameter = 1.6 m Radius = r = 𝐷𝑖𝑎𝑚𝑒𝑡𝑒𝑟/2 = (𝟏.𝟔)/𝟐 = 16/(2 × 10) Area of table top = 𝜋r2 = 3.14 × (𝟖/𝟏𝟎)^𝟐 = 314/100 × 8/10 × 8/10 = (𝟑𝟏𝟒 × 𝟔𝟒)/𝟏𝟎𝟎𝟎𝟎 = 20096/10000 = 2.0096 m2 Now, Cost of polishing 1 m2 area = Rs 15 Cost of polishing 2.0096 m2 area = Rs 15 × 2.0096 = Rs 15 × 𝟐𝟎𝟎𝟗𝟔/𝟏𝟎𝟎𝟎𝟎 = Rs 3 × 20096/2000 = Rs 3 × 𝟏𝟎𝟎𝟒𝟖/𝟏𝟎𝟎𝟎 = Rs 30144/1000 = Rs 30.144 = Rs 30.14 (approx.) ∴ It will cost Rs 30.14 (approx.) to polish the table top

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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.