Question

A sea shell contains 90% as much C-14 as a living shell of the same size.how old is it? approximately how many years did it take for its C-14 content to diminish from its initial value to 99% of that?(half life time of C-14 is 5570 years).

Answer 1

1)    Age of Sea Shell : it contains 90% = 0.9
       age = - T1/2  Ln 0.9 / Ln 2 = 846.66 years

2)   age when C-14 was 99% : - T1/2  Ln 0.99 / Ln 2 = 80.76 yrs
       Duration for C-14 content to diminish to 90% from 99% : 765.9 years