The sample currently contains five atoms of Lead-207 for every three atoms of Uranium-235.
How long ago did the meteorite solidify?
5.2×1085.2 \times 10^85.2×108 years
7.4×1087.4 \times 10^87.4×108 years
9.9×1089.9 \times 10^89.9×108 years
1.9×1091.9 \times 10^91.9×109 years
