Question 966745
The can that holds the balls is a cylinder with the diameter equal to the diameter of the ball and the height equal to 3 diameters.

Find the diameter of the ball.
{{{V[b]=(4/3)pi(D/2)^3}}}
{{{36pi=(pi/6)D^3}}}
{{{D^3=216}}}
{{{D=6}}}{{{cm}}}
So then the volume of the cylinder is,
{{{V[c]=pi(6/2)^2(3(6))}}}
{{{V[c]=162pi}}}
So then the empty space is,
{{{V[ES]=V[c]-3B[v]}}}
{{{V[ES]=162pi-3(36pi)}}}
{{{V[ES]=162pi-108pi}}}
{{{highlight(V[ES]=54pi)}}}