Q.If the ratio of the radii of two perpendicular solid cones is 2:3 and the ratio of their heights is 5:3, what is the ratio of their volumes ? (a) 27:20 (b) 20:27 (c) 4:9 (d) 9:4
Answer: B
The ratio of the volumes is = \(\pi r_1^2h_1:\pi r_2^2h_2=\cfrac{r_1^2h_1}{r_2^2h_2}\)
\(=\left( \cfrac{r_1}{r_2}\right)^2\times \cfrac{h_1}{h_2}=\left( \cfrac{2}{3}\right)^2\times \cfrac{5}{3}=\cfrac{4}{9}\times \cfrac{5}{3} \)
\(=20:27\)
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