Enter your answer in the provided box.

$$

The approximate date of a San Francisco earthquake is to be found by measuring the $14$C activity

$($t$1/2=5730.$ yr$)$

of parts of a tree uprooted during the event. The tree parts have an activity of

$12\mathrm{.}9$ d$/$min

$$

g C$,$

and a living tree has an activity of

$15\mathrm{.}3$ d$/$min

$$

g C$.$

How long ago did the earthquake occur?

$$