The volume of the figure = volume of first cone + volume of second cone + volume of a hemisphere
Formula
Volume of a cone = 1/3πr²h
The volume of hemisphere = 2/3πr³
Therefore
r = radius , h = height
where h1 = 20in , h2 = 18in and r = 15in
Volume of the first cone = 1/3πr²h1
= 1/3 x π x (15)² x 20
= 1500π in³
Volume of the second cone = 1/3πr²h2
= 1/3 x π x (15)² x 18
= 1350π in³
Volume of hemisphere = 2/3πr³
= 2/3 x π x (15)³
= 2250π in³
Therefore
The volume of the figure = 1500π in³ + 1350π in³ + 2250π in³
= 5100π in³
Hence the volume of the figure = 5100π in³