Geometry

Question Analysis:
This problem tests understanding that the volume formula applies to any prism, regardless of base shape.
The main focus is recognizing that "distance between bases" means height.

Key Concept Explanation:
For any prism: Volume = Base Area × Height.
The base can be any polygon - the formula remains the same.

Step-by-Step Solution:
Write the volume formula: 420 = 30 × Height
Solve for height: 420 ÷ 30 = 14 cm

Common Mistakes:
Confusing "distance between bases" with other dimensions.