A fossil was analyzed and determined to have a carbon14 leve

Solution

remember first order kinetics
ln2 = k*t1/2 so k = ln2 / t1/2 = 1.21*10^-4 yr-1
ln([A]t / [A]o) = -k*t
t = -ln([A]t / [A]o) / k
[A]t / [A]o = 0.38 (38%)
so
t = -ln(0.38 ) / 1.21*10^-4 = 7996.7 yr