Ok let's do this:

The cone has a height of 4.4cm, the radius is 3.5 (same as hemisphere)

Let's do the cone first:

So grab the volume formula

You do it from there.

Now do the hemisphere

Sphere Formula:

you need to divide by 2 because it is half of sphere

substitute radius in:

You do it from there.

Then add together and done.

Second question:

Square based pyramid: The base has sides of 230m and the height is 147m.

I'm assuming the "material" is the volume... if I have misunderstood something then please say so...

Grab the formula:

So we need 2592100 "material" to build a square based pyramid with base sides of 200m

Get the formula out again:

Substitute:

<--- divide 200 two times.

<---- divide by 1/3 which is multiply by 3.

There's your height. The pyramid should use the same material.

Check:

<---- basically the same..

ok that's it.