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Sphere or balloon: link the rates of its radius, surface area and volume

This type of question, asked 8 times: 10 May 2023 S2, 10 May 2024 S2, 13 Apr 2026 S1, 15 Apr 2026 S2, 16 Apr 2026 S2, 19 Apr 2026 S2, 13 May 2026 S1, 13 May 2026 S2. All 8 questions below, oldest first.

Try each one first, then open its answer.

  1. Question 1

    10 May 2023 S2

    106
    The volume of a ball is increasing at the rate of 4π4\pi cc/sec. The rate of increase of the radius, when the volume is 288π288\pi cc, is

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  2. Question 2

    10 May 2024 S2

    108
    If the surface area of a spherical balloon of radius 6 cm is increasing at the rate 2 cm2/sec2\,\text{cm}^2/\text{sec}, then the rate of increase in its volume in cm3/sec\text{cm}^3/\text{sec} is

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  3. Question 3

    13 Apr 2026 S1

    76
    If a spherical balloon has a variable diameter 3x+923x + \dfrac{9}{2} units, then the rate of change of its volume with respect to xx is

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  4. Question 4

    15 Apr 2026 S2

    74
    The surface area of a spherical ball is increasing at the rate of 4π cm24\pi\ \mathrm{cm^2}/second. The rate at which the radius is increasing when the surface area is 16π cm216\pi\ \mathrm{cm^2} is

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  5. Question 5

    16 Apr 2026 S2

    75
    A spherical snow ball is melting so that its volume is decreasing at the rate of 8 c.c./sec then the rate of change of radius when the radius is 2 cm, is :

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  6. Question 6

    19 Apr 2026 S2

    76
    If the rate of increase of surface area of a spherical balloon is 5 cm2/sec5\ \mathrm{cm^2/sec} and rate of increase of volume of a spherical balloon is 10 cm3/sec10\ \mathrm{cm^3/sec}, then the radius of the balloon at that time is...

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  7. Question 7

    13 May 2026 S1

    76
    The radius of a spherical soap bubble is increasing at a constant rate of 0.50.5 cm/sec. At the instant when the radius is 55 cm, the rate at which its volume is increasing is...

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  8. Question 8

    13 May 2026 S2

    78
    The radius of a spherical balloon increases at the rate of 44 cm/sec. The rate at which its surface area increases, when the radius is 55 metres is

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