Finding Earth's orbital period from mass and distance

[Demin]

Homework Statement

Whats the Earth's orbital period around the sun if mE=5.98x10^24kg , mS =2x10^30kg,
r = 1.5x10^11

Homework Equations

T^2= kr^3

The Attempt at a Solution

i can figure out the period easily w/ 2 radii + 1 period

 

[Shooting Star]

Assuming that the orbit is circular, use grav force on Earth due to sun is equal to the centrpetal force. Also, T=2pi/omega.

 

[Demin]

cant use omega ,,answer has to be in sec not rads :(

 

[Shooting Star]

That's why I'd given the relation between T and omega.