Given that the Russian GLONASS system has an orbital altitude of 19,140 Km and a period of revolution of 11 hours and 15 minutes, the US system has an orbital altitude of 20,180 Km and a period of revolution of 11 hours and 58 minutes and finally the Galileo system an orbital altitude of 23,222 Km and a period of revolution of 14 hours and 22 minutes, how does one calculate the period of revolution for the Chinese Compass system with an orbital altitude of 21,150 Km?
EDIT: I used Kepler's third law in my original calculation, but assumed that the orbital altitudes given are referenced to the centre of the earth. I made this assumption based on how I interpreted the math, and did not know that the orbital altitudes are referenced to mean sea level on Earth. Once I added the radius of the earth which is approximately 6,371 Km to the orbital altitudes I was able to calculate the period of revolution. So the actual orbital distance from the centre of the earth to the Chinese Compass system is 21,150 Km + 6,371 Km.