Finding ortibal period and orbital speed PLEASE HELP

[mandi_babe1]

Homework Statement

GPS (Global Positioning System) satellites orbit at an altitude of 2.6×107 .
Find the orbital period.
Find the orbital speed of such a satellite.

Homework Equations

I would like to know how to approach this. I don't know where to start w/o other figures.

The Attempt at a Solution

I went through a long, convoluted process and determined 2.8*10^29, which is entirely wrong. Please help!
Thank you in advance!

 

[mgb_phys]

In orbit the centrifugal force (F=m w^2 r) balances the gravitational force (F=GMm/r^2)
Where w is the angular speed (radians/sec)

(or see http://en.wikipedia.org/wiki/Orbital_period#Small_body_orbiting_a_central_body)

hint. The answer only depends on the mass of the Earth M, and r is from the center of the Earth - not the height above the surface.