A radioactive isotope of Bismuth undergoes Beta Decay with a half-life of 22 days. How long (in days) will it take the Activity (A) of the sample to decrease to one-ninth of its original value? Assume that the original activity is A0.

Answer 1

just find t where
(1/2)^(t/22) = 1/9

The value of A0 does not matter, as it will be on both sides of the equation.

(t/22) log(1/2) = log(1/9)
Now just churn the numbers.