GSEB Std 10 (SSC) • 2022 • 3 Marks

Surface Areas and Volumes: Surface Area Melting & Recasting

Official examination question with verified M1/A1 mark scheme and step-by-step mathematical reasoning.

Problem Statement

Metallic spheres of radii $6\text{ cm}, 8\text{ cm}$ and $10\text{ cm}$ respectively are melted to form a single solid sphere. Find the radius of the resulting sphere.

Verified Solution & Marking Scheme

Equate Volumes
Volume of resulting sphere equals sum of volumes of three smaller spheres: $\frac{4}{3}\pi R^3 = \frac{4}{3}\pi r_1^3 + \frac{4}{3}\pi r_2^3 + \frac{4}{3}\pi r_3^3$
Calculate Cubes
$R^3 = 6^3 + 8^3 + 10^3 = 216 + 512 + 1000 = 1728$
Find Cube Root
$R = \sqrt[3]{1728} = 12\text{ cm}$
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