Carbon- 14 is a radioactive isotope used to date objects. If \(A_{0}\)
represents the initial amount of carbon- 14 in the object, then the quantity
remaining at time \(t\), in years, is
$$
A(t)=A_{0} e^{-0.000121 t}
$$
(a) A tree, originally containing 185 micrograms of carbon- 14 , is now 500
years old. At what rate is the carbon- 14 decaying?
(b) In 1988 , scientists found that the Shroud of Turin, which was reputed to
be the burial cloth of Jesus, contained \(91 \%\) of the amount of carbon- 14 in
freshly made cloth of the same material. \({ }^{6}\) According to this data, how
old was the Shroud of Turin in 1988 ?