2016 · Q58
The height of a cone is 60 cm. A small cone is cut off at the top by a plane parallel to the base and its volume is 1/64 the volume of original cone. What is the height from the base at which the section is made ?
Elementary MathematicsMensuration
- A15 cm
- B20 cm
- C30 cm
- D45 cm
Explanation
Volume ratio 1/64 means the linear ratio is ∛(1/64) = 1/4, so the small top cone is 60/4 = 15 cm tall. The section is therefore made 60−15 = 45 cm above the base (option D).