How fast is the balloon growing?

MediumCalculus~4m

Air is pumped into a spherical balloon at a constant 100100 cm³/s. At the instant the radius is 55 cm, how fast is the radius increasing (in cm/s)? Give a decimal to four places.

Show hints (2)+
  1. Differentiate V=43πr3V=\tfrac43\pi r^3 with respect to time: dVdt=4πr2drdt\tfrac{dV}{dt}=4\pi r^2\tfrac{dr}{dt}.
  2. Solve for drdt\tfrac{dr}{dt} with dVdt=100\tfrac{dV}{dt}=100, r=5r=5.

Answer

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0.3183 (± 0.001)

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