You can find the volume by using the formula of density
[tex]d=\frac{m}{v}[/tex]
where d is the density, m is the mass and v is the volume
You have to solve the formula for v like this:
[tex]v = \frac{m}{d} [/tex]
you have the density and the mass so you just have to replace the variables in the formula with the values they are giving you, like this:
[tex]v = \frac{9842mg}{1406 \frac{mg}{ml} } = 7ml[/tex]
The volume of the stone is 7ml