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Two solid metallic right circular cones of heights 31 cm and 53 cm and radii of their bases 21 cm each are melted and recast into a solid s…

3621Medium DSSSB TGT Computer Science 0 replies 2 views

Two solid metallic right circular cones of heights 31 cm and 53 cm and radii of their bases 21 cm each are melted and recast into a solid sphere. What is the surface area (in cm²) of the sphere?

A1764π
B900π
C1600π
D1296π

Correct answer: A

Explanation

Total volume = (1/3)π × 21² × (31 + 53) = 12348π. For the sphere, (4/3)R³ = 12348 gives R³ = 9261, so R = 21 cm. Surface area = 4π × 21² = 1764π cm².

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