Geometry

Question Analysis
This question requires first finding the radius from the given diameter and then using the sphere volume formula to calculate the amount of air the balloon can hold.
The main focus is on understanding the relationship between diameter and radius and applying the formula correctly in a practical situation.

Key Concept Explanation
The relationship between the diameter and the radius of a sphere is .
Once the radius is determined, the volume of the sphere can be calculated using the formula .

Step-by-Step Solution
Calculate the radius of the balloon: Given inches, so inches.
Substitute the radius into the volume formula: