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MHT CET · Maths · Application of Derivatives

The rate of change of volume of spherical balloon at any instant is directly proportional to its surface area. If initially its radius is 3 cm , after 2 minutes its radius becomes 9 cm , then radius of balloon after 4 minutes is

  1. A 12 cm
  2. B 14 cm
  3. C 15 cm
  4. D 18 cm
Verified Solution

Answer & Solution

Correct Answer

(C) 15 cm

Step-by-step Solution

Detailed explanation

\( \frac{dV}{dt} = kA \) \( \frac{d}{dt}\left(\frac{4}{3}\pi r^3\right) = k(4\pi r^2) \)