ICSE Class 10 • 2024 • 3 Marks

Mensuration: Recasting Cone into Sphere Radius

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

Problem Statement

A metallic solid cone of height $24\text{ cm}$ and base radius $6\text{ cm}$ is melted and reshaped into the shape of a solid sphere. Find the radius of the sphere.

Verified Solution & Marking Scheme

Equate Volumes of Cone and Sphere
$\text{Volume of cone} = \frac{1}{3}\pi r_{\text{cone}}^2 h = \frac{1}{3}\pi (6^2)(24) = \frac{1}{3}\pi (36)(24) = 288\pi\text{ cm}^3$ $\text{Volume of sphere} = \frac{4}{3}\pi R^3$ $\frac{4}{3}\pi R^3 = 288\pi$
Solve for Sphere Radius R
$\frac{4}{3} R^3 = 288 \implies R^3 = 288 \times \frac{3}{4} = 72 \times 3 = 216$ $R = \sqrt[3]{216} = 6\text{ cm}$
Practice this question with AI Socratic guidance on MonoMath →