Prehistoric cave paintings were discovered in a cave in France. The paint contained 15% of the original carbon-14. Estimate the age of the paintings. Use the formula.. "A=A0e^(-0.000121t)" to answer the question

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Answer:

We have to determine the time it takes for carbon 14 to decay to 15% of its original amount.

The half life of carbon 14 is 5,730 years

elapsed time = half life * log (beginning amount / ending amount) / log 2

elapsed time = 5,730 * log (100 / 15) / log 2

elapsed time = 5,730 * 0.82390874094 / 0.30102999566

elapsed time = 5,730 * 2.7369655942

elapsed time = 15,683 years

= 15,700 years

Step-by-step explanation:

Solving the exponential equation, it is found that the painting is 15,679 years old.

The amount of carbon-14 after t years is modeled by the following equation:

[tex]A(t) = A(0)e^{-0.000121t}[/tex]

It retains 15% of the original amount, thus:

[tex]A(t) = 0.15A(0)[/tex]

Solving for t, we find the age.

[tex]0.15A(0) = A(0)e^{-0.000121t}[/tex]

[tex]e^{-0.000121t} = 0.15[/tex]

[tex]\ln{e^{-0.000121t}} = \ln{0.15}[/tex]

[tex]-0.000121t = \ln{0.15}[/tex]

[tex]t = -\frac{\ln{0.15}}{0.000121}[/tex]

[tex]t = 15679[/tex]

The painting is 15,679 years old.

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