@(you need an account to see links) Not sure if I did 2nd one correctly but I'm pretty sure about #1
1.
A(T) = Ao * e^(kT)
.5A = A * e^(kT)
.5 = e ^ (kT)
ln .5 = kT
-.693 = 5730k
k = -.000121
.91 =e^(-.000121T)
ln .91 = -.000121T
-.0943 = -.000121T
T= 779.4 years
The table could not have belonged to King Arthur.