Question

The C-14 decay is used to estimate the age of an old dead tree. The activity of C-14 in the dead tree is determined to have fallen to 21% of its original value. C-14 has a half-life of 5700 years. Calculate, in years, the age of the dead tree.
I used the relevant formula but somehow my answer does not match with the markscheme. Can you help me?

Answer 1

From the calculations i did, its 1197. Is that the one you got?