Answer:
5700 years
Step-by-step explanation:
At time t=0, the amount of carbon present is:
C = 20e^0
C = 20
After one half-life, there will be half as much carbon, or 10 grams.
10 = 20e^(-0.0001216t)
0.5 = e^(-0.0001216t)
ln 0.5 = -0.0001216t
t = -(ln 0.5) / 0.0001216
t ≈ 5700
The half-life of carbon-14 is about 5700 years.
