Question

A farmer in China discovers a mammal hide that contains 37% of its original amount of C-14. Find the age of the mammal hide to the nearest year.

Answer 1

Answer: 54678 years

Step-by-step explanation:

This can be solved by the following equation:

$N_{t}=N_{o}e^{-\lambda t}$ (1)

Where:

$N_{t}=54\%=0.54$ is the quantity of atoms of carbon-14 left after time $t$

$N_{o}=1$ is the initial quantity of atoms of C-14 in the mammal hide

$\lambda$ is the rate constant for carbon-14 radioactive decay

$t$ is the time elapsed

On the other hand, $\lambda$ has a relation with the half life $h$ of the C-14, which is $5730 years$:

$\lambda=\frac{ln(2)}{h}=\frac{ln(2)}{5730 years}=1.21(10)^{-4} years^{-1}=0.000121 years^{-1}$ (2)

Substituting (2) in (1):

$0.54=1e^{-(0.000121 years^{-1}) t}$ (3)

Applying natural logarithm on both sides of the equation:

$ln(0.54)=ln(1e^{-(0.000121 years^{-1}) t})$ (4)

$-0.616=-(0.000121 years^{-1}) t$ (5)

Isolating $t$:

$t=\frac{-0.616}{-0.000121 years^{-1}}$ (6)

$t=54677.68 years \approx 54678 years$ (7)  This is the age of the mammal hide