Answer
$M=2.61\times 10^{41}Kg$
Work Step by Step
As we know that
$\frac{GMm}{r^2}=\frac{mv^2}{r}$
This can be rearranged as:
$M=\frac{v^2 r}{G}$
As $v=\frac{2\pi r}{T}$
$\implies M=\frac{(2\pi r)^2 r}{GT^2}$
We plug in the known values to obtain:
$M=\frac{2(3.1416(2.6\times 10^{20}))^2(2.6\times 10^{20})}{6.67\times 10^{-11}(200)^2}$
$M=2.61\times 10^{41}Kg$
