5.66%
The formula for calculating the percent mass/volume of a solution is expressed as:
[tex]\%m\text{/}v=\frac{mass\text{ of solute\lparen g\rparen}}{mass\text{ of solution \lparen g\rparen}}\times100[/tex]Given the following parameters
Mass of solute = 30000mg = 30g
Mass of solvent = 0.5litres = 500g
Mass of solution = 30g + 500g = 530g
Substitute the parameters into the formula
[tex]\begin{gathered} \%m\text{/}v=\frac{30g}{530g}\times100 \\ \%m\text{/}v=\frac{300}{53} \\ \%m\text{/}v=5.66\% \end{gathered}[/tex]Hence the percent mass/volume of a solution is 5.66%