cone volume = (pi*r*r*h)/3
where r is radius and h is height
Put in what we know
pi is about 3.1415
4 = (3.1415*3*3*h)/3
4 = 28.274*h/3
4 = 28.274/3*h
4 = 9.425*h
h = 4/9.425=0.424
and that would be in inches so
Height is about 0.424 inches.
It can be rounded to 0.42