Answer
Please see the work below.
Work Step by Step
We know that
$T=\frac{2\pi}{\sqrt{GM_s}}r^{\frac{3}{2}}$
We plug in the known values to obtain:
$T(\frac{3.16\times 10^7s}{1year})=[\frac{2\pi}{\sqrt{(6.67\times 10^{-11}N.m^2/Kg^2)(2.0\times 10^{30}Kg)}}][(r)(\frac{1.5\times 10^{11}m}{1A.U})]^{\frac{3}{2}}$
This simplifies to:
$T=(\frac{1year}{(A.U)^{\frac{3}{2}}})r^{\frac{3}{2}}$
$\implies T=Cr^{\frac{3}{2}}$
