A balloon, which always remains spherical, has a variable radius. Find the rate at which its volume is increasing with respect to its radius when the radius is 7 cm.

Explanation

To find the rate at which the volume of a spherical balloon is increasing with respect to its radius when the radius is 7 cm, we can follow these steps:

### Step 1: Write the formula for the volume of a sphere.
The volume \( V \) of a sphere is given by the formula:
\[ V = \frac{4}{3} \pi r^3 \]

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