Apentix/AP Calculus AB/Unit 4: Contextual Applications of Differentiation/Question

AP Calculus ABmediummcq1 pt

The radius of a circular puddle increases at 3 cm/s. How fast is the puddle's area increasing when the radius is 10 cm?

A.

20\pi

cm

^2

/s

B.

60\pi

cm

^2

/s

C.

30\pi

cm

^2

/s

D.

6\pi

cm

^2

/s

Explanation

Core Concept

From $A=\pi r^2$ , $\dfrac{dA}{dt}=2\pi r\dfrac{dr}{dt}=2\pi(10)(3)=60\pi$ cm $^2$ /s.

Correct Answer

B $60\pi$ cm $^2$ /s

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