Using an Exponential Decay Formula
Carbon dating is used by scientists to find the age of fossils, bones, and other items. The formula used in carbon dating is
P(t) = P_02^{-t/5600}
where P_0 represents the original amount of carbon-14 (C_{14}) present and P(t) represents the amount of C_{14} present after t years. If 10 mg of C_{14} is present in an animal bone recently excavated, how many milligrams will be present in 3000 years?
Substituting the values in the formula gives
P(t) = P_02^{-t/5600}
P(3000) = 10(2)^{-3000/5600}
≈ 10(2)^{-0.54} (Recall that ≈ means “is approximately equal to.”)
≈ 10(0.69)
≈ 6.9 mg
Thus, in 3000 years, approximately 6.9 mg of the original 10 mg of C_{14} will remain.