Refer to the exponential decay model in Example 3. How many milligrams of 14C would have to be present at the beginning in order to have 25 milligrams present after 18,000 years? Compute the answer to the nearest milligram.

Data from Example 3

Cosmic-ray bombardment of the atmosphere produces neutrons, which in turn react with nitrogen to produce radioactive carbon-14 (¹⁴C). Radioactive ¹⁴C enters all living tissues through carbon dioxide, which is first absorbed by plants. As long as a plant or animal is alive, ¹⁴C is maintained in the living organism at a constant level. Once the organism dies, however, 14C decays according to the equation

where A is the amount present after t years and A₀ is the amount present at time t = 0.

Transcribed Image Text:

A = Age Age-0.000124t