Q131 of 131 Page 226

A photograph of Billiard/Snooker table has dimensions as th of its actual size as shown in Fig. 9.71:


The portion excluding six holes each of diameter 0.5 cm needs to be polished at rate of Rs. 200 per m2. Find the cost of polishing.

Since the photograph has dimensions as th of its actual size, hence


Actual length = 25 × 10 = 250 cm


Actual breadth = 10 × 10 = 100 cm


Actual area of the table = 250 × 100 = 25,000 cm2


Diameter of 1 hole = 0.5 × 10 = 5 cm


Radius of 1 hole = 2.5 cm


Area of 6 holes = 6 × ∏r2 = 6 × × 2.5 × 2.5 = 118 cm2


Area to be polished = Area of table – Area of 6 holes = 25,000 – 118 = 24,882 cm2 = 2.4882 m2


∴ Cost of polishing at the rate of Rs 200/ m2 = 2.4882 × 200 = Rs 497


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