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Air is pumped into an empty spherical balloon at $10$ m$^3$/sec for $8$ seconds.

At what rate is the diameter changing when the diameter reaches $2$ m?

$\cfrac{5}{\pi}$ m/sec

$\cfrac{10}{\pi}$ m/sec

$\cfrac{5}{2}$ m/sec

$\cfrac{2\pi}{5}$ m/sec