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Ex 13.3, 6 - The slant height and base diameter of a conical - Area Of Cone

  1. Chapter 13 Class 9 Surface Areas and Volumes
  2. Serial order wise
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Ex 13.3, 6 The slant height and base diameter of a conical tomb are 25 m and 14 m respectively. Find the cost of white-washing its curved surface at the rate of Rs 210 per 100 m2. Curved surface area of tomb = πrl Given slant height = l = 25m Radius = 14/2 = 7m Curved surface area of tomb = πrl = (22/7×7×25) m2 = (22×1×25) m2 = 550m2 Cost of whitewashing 100 m2 area = Rs 210 Cost of whitewashing 1 m2 area = Rs 1/100 × 210 Cost of whitewashing 550 m2 area = Rs 1/100 × 210 × 550 = Rs 1155 Therefore, the cost of whitewashing the tomb is Rs 1155

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