Dating System Age of half-life
238U -> 206Pb 4.5 Billion Years
235U -> 207Pb 713 Million Years
40K -> 40Ar 1.3 Billion Years
14C -> 14N 5730 Year
A Rock Originally has 2200 atoms of 235U and no 207Pb. it now has 800 atoms of 235U. Assuming the only chemicals process is the radioactive decay of Uranium to Lead, what is the age of the rocks?