we know that
The density is equal to the formula
[tex]Density=\frac{mass}{volume}[/tex]
in this problem we have
[tex]mass=23.401\ gr[/tex]
Find the volume of a piece of green jade
[tex]Volume=56.5\ ml-50.0\ ml=6.5\ ml[/tex]
Substitute the values in the formula of density
[tex]Density=\frac{23.401}{6.5}[/tex]
[tex]Density=3.60\frac{gr}{ml}[/tex]
therefore
the answer is
[tex]Density=3.60\frac{gr}{ml}[/tex]