With these math questions final part

#9).    The volume of a sphere is          (4/3) (pi) (radius)³ .    

You have a small sphere inside of a larger sphere.
The radius of the small sphere inside is 6mm.
The radius of the large sphere outside is 9mm.
They want to know the volume of the SHELL . . .
that's:

 (volume of the big sphere) minus (volume of the small inside sphere).

#10).  Here's where it all comes together !

A). The volume of a cylinder is            (pi) (radius)² (height) .

B). The volume of a sphere is             (4/3) (pi) (radius)³ .

C). The volume of a cone is                (1/3) (pi) (radius)² (height) . 

The question gives you all the numbers.  All  you have to do is
take each formula, write the numbers into it, and find out which
choice has the greatest volume.

You can do it !

Iam thinking the answer is a.) knew