An expandable cone-shaped funnel consists of two sections as shown. (a) what is the volume of the bottom section? (b) what is the volume of the top section?

We know that
volume of a cone=(1/3)*pi*r²*h

Part a) What is the volume of the bottom section? 
diameter=6 cm
r=6/2> r=3 cm
h=8 cm
Volume=(1/3)*pi*3²*8> 24*pi cm³> 75.36 cm³

Part b)What is the volume of the top section?
diameter=12 cm
r=12/2> r=6 cm
h=16 cm
Volume=(1/3)*pi*6²*16> 192*pi cm³> 602.88 cm³

alternative method to find the volume of the top section

we know that
volume larger cone=scale factor³*volume smaller cone

scale factor=16/8> 2
volume  smaller cone=24*pi cm³
so
volume larger cone=2³*24*pi> 8*24*pi > 192*pi cm³