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MATHS help plizzz

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A spherical balloon is being inflated and its radius is changing at the rate of 2m/minute. When the radius is 4m, find the rate at which the:

(a).volume is increasing

V= 3/4 pie r^2

(b). surface area is increasing

A = 4 pie r^2

  • MATHS help plizzz - ,

    Your formula for volume is incorrect.
    V = (4/3)πr^3
    dV/dt = 4πr^2 dr/dt
    so when r = 4
    dV/dt = 4π(16)(2) = 72π cm^3/minute

    A = 4πr^2
    dA/dt = 8πr dr/dt
    when r=4
    dA/dt = 8π(4)(2) = 64π cm^2/min

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