truncated cone
They still subject people to these ?

We saw them in the alst year of HS, never needed to know anything about them again (and I'm an engineer).

What i think:

first a formula for the area of a cirkel:

2 pi int(r dr)

now integrate it over the height

2 pi int(int(r dr) dx)

with dr/dx =0.1 -> dx=10dr

20 pi int(int(r)dr dr )

You now have a double integral over r, solving it you get

20/6 pi r^3 between r=3 and r=4

calculate that and you should get the volume.

I checked using the basic cone formulas, it should be correct, i hope this isn't for credit ...