A photograph of Billiard/Snooker table has dimensions as 110th of its actual size as shown in the given figure: - Mathematics

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Sum

A photograph of Billiard/Snooker table has dimensions as `1/10`th of its actual size as shown in the given figure:


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

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Solution

Actual length = 25 × 10 = 250 cm

Actual breadth = 10 × 10 = 100 cm

Area of table = 250 × 100 = 25000 cm2

Radius of 1 hole = `0.5/2` = 0.25 cm

Area of 6 holes = 6 × πr2 = `6 xx 22/7 xx 0.25 xx 0.25` = 1.18 cm2

Area of portion excluding holes = 25000 – 1.18 = 24998.8 cm2

∴ Cost of polishing = ₹ `24999/10000 xx 200` = ₹ 500 (approx.)

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Chapter 9: Perimeter and Area - Exercise [Page 299]

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NCERT Exemplar Mathematics Class 7
Chapter 9 Perimeter and Area
Exercise | Q 131. | Page 299

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