Relation between Slant Height and Height of a Right Circular Cone

Q.

The formula to find the slant height of the cone is?

Q. The base radii of two right circular cones of the same height are in the ratio 3 : 5. The ratio of their volumes is

1. $r_2^2:r_1^2$
2. $2r_1^2:r_2^2$
3. $25:9$
4. $9:25$