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Question 310004
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Application of Derivatives: Rate of change MCQ

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Rate of changeEasyQuestion 310004

Question

If the radius of a circle increases at 2 cm/s, the rate of increase of area when r = 5 cm is:
  1. A
    20π cm²/s
    Correct
  2. B
    10π cm²/s
  3. C
    25π cm²/s
  4. D
    4π cm²/s

Correct answer

20π cm²/s

Explanation

A = πr². dA/dt = 2πr(dr/dt) = 2π(5)(2) = 20π cm²/s.

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