Question

The half-life of cobalt-60 is 5.20 yr. how many milligrams of a 2.000-mg sample remain after 10.50 years?

Answer 1

final amount =initial anount *(1/2)^(t/half life)

final amount =2.000 mg *(1/2)^(10.5/5.20) = 0.493 mg remain after 10.5 years