# QA – Placement Quizzes | Mensuration 3D | Question 15

The radii of two cones are in the ratio 2:1, their volumes are equal. Find the ratio of their heights.**(A)** 1:8**(B)** 1:4**(C)** 2:1**(D)** 4:1**Answer:** **(B)****Explanation:** Let the radius and height of the two cones be R, H and r, h respectively such that R:r = 2:1. Then,

Volume of the cone C = 1/3 * π * R² * H

Volume of the cone c = 1/3 * π * r² * h

Now,

1/3 * π * R² * H = 1/3 * π * r² * h

H:h = r²:R² = 1²:2² = 1:4.

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