Ratio of Land Areas

XAT 2025 · Quantitative Ability & Data Interpretation · Easy · Geometry

Adu and Amu have bought two pieces of land on the Moon from an e-store. Both the pieces of land have the same perimeters, but Adu's piece of land is in the shape of a square, while Amu's piece of land is in the shape of a circle. The ratio of the areas of Adu's piece of land to Amu's piece of land is:

  1. A.

    1 : 1

  2. B.

    π2:4\pi^2 : 4

  3. C.

    1 : π\pi

  4. D.

    π:4\pi : 4

  5. E.

    π:2\pi : 2

Answer

D

Explanation

Let the perimeter be PP. For Adu's square land: side s=P4s = \frac{P}{4}, Area A1=s2=P216A_1 = s^2 = \frac{P^2}{16}. For Amu's circular land: 2πr=P  ⟹  r=P2π2\pi r = P \implies r = \frac{P}{2\pi}, Area A2=πr2=π(P2π)2=P24πA_2 = \pi r^2 = \pi \left(\frac{P}{2\pi}\right)^2 = \frac{P^2}{4\pi}. Ratio of areas A1:A2=P216:P24π=116:14π=π4=π:4A_1 : A_2 = \frac{P^2}{16} : \frac{P^2}{4\pi} = \frac{1}{16} : \frac{1}{4\pi} = \frac{\pi}{4} = \pi : 4.

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