An environmental monitoring laboratory analyzes two radioisotopes, Isotope X X\,X and Isotope YYY. A pure sample of Isotope X X\,X containing N N\,N nuclei has an activity AAA. The half-life of Isotope X X\,X is 12 years12\text{ years}12 years.
A pure sample of Isotope Y Y\,Y containing 3N nuclei has an activity of 0.4A.
What is the half-life of Isotope YYY?
10 years10\text{ years}10 years
90 years90\text{ years}90 years
14.4 years14.4\text{ years}14.4 years
1.6 years1.6\text{ years}1.6 years
