Q.The ratio of the base radii of two right circular cones is 2 : 3, and the ratio of their heights is 3 : 2. Then the ratio of their volumes is — (a) 3:2 (b) 9:4 (c) 4:9 (d) 2:3
Answer: D
Let the radii of the two right circular cones be \(2r\) units and \(3r\) units respectively, and their heights be \(3h\) units and \(2h\) units respectively. \(\therefore\) The ratio of their volumes \(= \cfrac{1}{3}\pi(2r)^2 \times 3h : \cfrac{1}{3}\pi(3r)^2 \times 2h\) \(= 12r^2h : 18r^2h\) \(= 2 : 3\)
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