2026 · Q56
A well is dug with a diameter of 3.5 m and 16 m depth. The earth soil so excavated is spread in the form of a right circular cone of radius 7 m. What is the height of the cone?
Elementary MathematicsMensuration
- A1.5 m
- B2 m
- C2.5 m
- D3 m
Explanation
The excavated earth is a cylinder of radius 1.75 m and depth 16 m, volume π(1.75)²·16. Spread as a cone of radius 7 m and height H, its volume is (1/3)π·49·H. Equating, (1.75)²·16 = 49H/3, so H = 3·3.0625·16/49 = 147/49 = 3 m, option D.