$7$

$8$

A metal ball$-$bearing with a circumference of $45\mathrm{.}1mm$ weighs $6\mathrm{.}25g($circumference of a circle $=2r.$ What is the density of the metal in $\frac{g}{c{m}^3}?$ Be sure your answer has the correct number of significant figures.

Note: Reference the Volume formulas table for additional information.