I need help with meetings of lead?
gave a half life of 235U carry 207Pb (), 7,13 x 10 ^ 8 years, calculate the age of a grain of zircon from granite, which contains 6.25% of 207Pb formed by the decay and 93.75% of the parent isotope 235U.
Now it is a question of disintegration radioactive. 0.9375 = (1 / 2) ^ (and / (7.13 * 10 ^ 8)) ^ 2 (and / (7.13 * 10 ^ 8)) = 1/0.9375 log [2] (1/0.9375) = S / (7.13 * 10 ^ 
y = (7.13 * 10 ^ * log [2] (1/0.9375) y = 6.64 = 66,387,005.33 * 10 ^ 7 years
JMDMT #1100 Microfossils of Cyanobacteria in Carbonaceous Meteorites