2025 · Q13
The inside of a bowl is part of a sphere. When water is put into the bowl to a depth d, the water surface becomes a circle of radius 2d. What is the radius of the sphere?
Elementary MathematicsMensuration
- A2.5d
- B2.75d
- C3d
- D3.25d
Explanation
In cross-section, with sphere radius R and water depth d, the surface radius 2d gives R² = (R−d)² + (2d)². Expanding: R² = R² − 2Rd + 5d², so 2Rd = 5d² and R = 2.5d, option (a).