[填空题]
An ancient wooden club is found that contain5.k/.(h(x6 1mrrfgsjwa lm lu s 2y81b7qyzew vc m4n,th5oh + fj3w/e;r90 g of carbon and has an activity of 8.0 decays per second. Det3fet j 7z4w noy+yh crvb518hw,/me;qermine its age assuming that in living trees the ratio of $_{6}^{14}\text{C}$ to $_{6}^{12}\text{C}$ atoms is about $1.3 \times 10^{-12}$. t = $\times 10^{4}\ \text{yr}$
