A laboratory investigation shows that a sample of uranium ore contains 9.61 mg of
_(92)^(238)U
(molar mass
238.05079(g)/(m)ol
) and
2.16mg
of
828Pb
(molar mass
205.97447(g)/(m)o
. Calculate the age of the ore. The hali-life of
_(92)^(238)U
is
4.5\times 10^(9)yr
.