ExamBro
ExamBro
CUET · MATHS · PYQ PAPER 2025

The rate of change of volume of a sphere with respect to its surface area, when the radius is 6 cm is:

  1. A \(1 \mathrm{~cm}^3 / \mathrm{cm}^2\)
  2. B \(6 \mathrm{~cm}^3 / \mathrm{cm}^2\)
  3. C \(2 \mathrm{~cm}^3 / \mathrm{cm}^2\)
  4. D \(3 \mathrm{~cm}^3 / \mathrm{cm}^2\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(3 \mathrm{~cm}^3 / \mathrm{cm}^2\)

Step-by-step Solution

Detailed explanation

\(V = \frac{4}{3} \pi r^3\), \(\frac{dV}{dr} = 4 \pi r^2\) \(A = 4 \pi r^2\), \(\frac{dA}{dr} = 8 \pi r\) \(\frac{dV}{dA} = \frac{dV/dr}{dA/dr} = \frac{4 \pi r^2}{8 \pi r} = \frac{r}{2}\) For \(r = 6\): \(\frac{dV}{dA} = \frac{6}{2} = 3 \, \mathrm{cm}^3 / \mathrm{cm}^2\)