Q.

Two cones have their heights in the ratio 1 : 3 and radii in the ratio 3 : 1. Then ratio of their volume is:

1 1 : 3  
2 2 : 3  
3 3 : 1  
4 1 : 1  

Ans.

(3)

Let height of the cones are h and 3h respectively and their radii are 3r and r respectively.

∴ Ratio of volumes = volume of first conevolume of second cone=13π(3r)2×h13πr2×3h=93=31 Required ratio is 3 : 1.