How many cones equal one cylinder (same r and h): A right circular cylinder is completely filled with water. How many right circular cones with the same radius and height are needed to store the same water?

Difficulty: Easy

Correct Answer: 3

Explanation:


Introduction / Context:
This tests the known volume relationship between a cylinder and a cone with identical radius and height. It is a standard ratio result used often in mensuration.


Given Data / Assumptions:

  • Same radius r and height h for both solids.
  • V_cylinder = π r^2 h; V_cone = (1/3) π r^2 h.


Concept / Approach:

  • Compare the formulas to find how many cones equal one cylinder.


Step-by-Step Solution:

V_cylinder / V_cone = (π r^2 h) / ((1/3) π r^2 h) = 3.Therefore, 3 cones of the same r and h equal the cylinder volume.


Verification / Alternative check:

Pick any r,h (e.g., r=1, h=1): V_cyl=π; V_cone=π/3; three cones give π.


Why Other Options Are Wrong:

  • 2/4/5: Do not match the derived exact ratio of 3.


Common Pitfalls:

  • Using 1/2 instead of 1/3 for the cone volume.
  • Forgetting the factor 1/3 attached to the cone formula.


Final Answer:

3

More Questions from Volume and Surface Area

Discussion & Comments

No comments yet. Be the first to comment!
Join Discussion