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The Brainliest Answer!
2016-03-18T18:37:57+05:30
Let the radius of the circular brass plate = r = 20 cm = 1/5 m
 Polishing rate = 450 rupees/m²
Total area of brass plate = Area of the circle, whose radius is 1/5 m
                                        = πr²
                                        = 3.14 × (1/5)²
Total area of a brass plate = 0.1256 m²
since we have 12 identical brass plat.
Total area to be Polished = 12(Area of one brass plate)
Total area to be polished = 12 × 0.1256 = 1.5072 m².
Total cost of polishing = Polishing rate × Total area.
There total cost of polishing = 450 × 1.5072 = 678.25 rupees
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