The radioactive element​ carbon-14 has a​ half-life of 5750 years. A scientist determined that the bones from a mastodon had lost 86.2​% of their​ carbon-14. Ho

Question

The radioactive element carbon-14 has a half-life of 5750 years. A scientist determined that the bones from a mastodon had lost 61.2% of their carbon-14. How old were the bones at the time they were discovered?

Answer 1

You can use the equation

fraction remaining = 0.5ⁿ where n is # of half lives elapsed 

n = ?

fraction remaining = 1 - 0.612 = 0.388

0.388 = 0.5ⁿ

n = 1.37 = the # of half lives

1.37 x 5750 yrs = 7881 years