Orbiting Galaxies Part B $(5$ pts$.)$

If we include dark matter, the two galaxies have a total mass of $6$x$1041$ kg$.$ What is the orbital period?

$($a$)$ About $2\mathrm{.}60$ x $1010$ yr $(8\mathrm{.}2$ x $1017$ s$)$

$($b$)$ About $1\mathrm{.}15$ x $1010$ yr $(3\mathrm{.}6$ x $1017$ s$)$

$($c$)$ About $4\mathrm{.}66$ x $109$ yr $(1\mathrm{.}5$ x $1017$ s$)$

$($d$)$ About $2\mathrm{.}26$ x $109$ yr $(7\mathrm{.}1$ x $1016$ s$)$

$($e$)$ About $5\mathrm{.}43$ x $108$ yr $(1\mathrm{.}7$ x $1015$ s$)$