The decay rate (k) is 2.2% per year = -0.022
The half life is ___ years.

Answer:
31.5 years.
Step-by-step explanation:
Half life is given by [tex]= -\frac{ln(2)}{k}[/tex]. Where we use the natural logarithm. Plugging in a value of [tex]k = -0.022[/tex] we get: 31.5 years for the half life.