Equal radius, equal volume — cylinder vs cone: A right circular cylinder and a right circular cone have the same radius and the same volume. Find the ratio of the height of the cylinder to the height of the cone.

Introduction / Context:
For solids with equal radius, comparing volumes quickly leads to a proportional relation between their heights. This question leverages the standard formulas for cylinder and cone volumes, focusing on their height relationship at equal volumes.

Given Data / Assumptions:

• Common radius r for both solids.
• Volumes are equal.

Concept / Approach:
Volume of cylinder = π r^2 * h_cyl. Volume of cone = (1/3) * π r^2 * h_cone. Setting these equal and cancelling common terms yields a simple ratio between heights.

Step-by-Step Solution:

Verification / Alternative check:
If h_cone = 30, then h_cyl = 10. Substituting gives equal volumes, confirming the ratio.

Why Other Options Are Wrong:
3 : 1 inverts the relation; 3 : 5 and 2 : 5 suggest mismatched formulas; 1 : 2 does not satisfy the equality of volumes for equal radii.

Common Pitfalls:
Forgetting the 1/3 factor in the cone’s volume; mixing radius equality with diameter or slant height.

Final Answer:
1 : 3