Question 1034021
We use
{{{A(t) = A[0](1/2)^(t/5600)}}}
Here {{{A(t) = .12*A[0]}}}
so we find t...
{{{.12A[0] = A[0](1/2)^(t/5600)}}}
{{{.12 = (1/2)^(t/5600)}}}
and, taking the log we get
{{{t/5600 = (ln .12)/(ln .5)}}}
so that
t = 17130 years
The best choice is B.