Question

Radioactive carbon-14 dating has determined that a fossil is 5:7 (103) years old. What is the total amount of the original (C14) still present in the fossil?

Answer 1

C14 has a half-life of 5730 years. the fraction of C14 remaining is
(1/2)^(5700/5730) = 0.5018

I expect they just wanted 1/2 as the answer.