For a cylinder, the volume, V, is given by:
where is the radius of the base of the cylinder, and is height of the cylinder.
when the height is 6, the volume is 300
.......divide both sides by 6
So, when the height goes to 2, the volume will be:
Now by Boyles' Law:
So the new volume is 100 cubic inches and the new pressure is 30 psi