Question

One specific toy is in the shape of a cone mounted on a cylinder. The total height of the toy is 110 mm and the height of its conical part is 77 mm. The diameters of the base of the conical part is 72 mm and that of the cylindrical part is 40 mm. (i) If its cylindrical part is to be painted red, the surface area need to be painted is (a) 2320 pie mm2 (b) 1120 pie mm2 (c) 1320 pie mm2 (d) 1720 pie mm2 ​

Answer 1

Given :-

• Total height of the toy = 110mm .
• Height of conical part = 77mm.
• Diameter of base of conical part = 72mm.
• Diameter of cylindrical part = 40mm.
• Cost of painting the toy = 3 paise for 32π mm²

To Find :-

• The surface area need to be painted red of cylindrical part ?

Solution :-

we know that,

• Radius = Diameter / 2 .
• CSA of cylinder = 2 * π * radius * height .
• Base Area of cylinder = π * (radius)²

so,

→ Cylindrical area painted = 2πrh + πr² = 2 * π * 20 * 33 + π * (20)² = 1320 π + 400π = 1720 mm². (Option D) (Ans.)

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