2) (directly borrowed from problem 520 in Dunlap) A simple method of calculating the age of the earth is based on the natural abundances of 23U and 23U. It is assumed that the quantities of these two isotopes were equal at the time that the earth was formed, and the measurements show that through natural attenuation the current relative abundances are 0.72%23U and 99.28%211U. Using the assumptions above and the respective half-lives of these two isotopes, 7.1108 years for 235U, and 4.51109 years for 238U, CALCULATE THE AGE OF PLANET EARTH