The given equation is:
[tex]a=0.65(0.92)^{t} [/tex]
The general equation for the radioactive decay can be written as:
[tex]a= a_{0}(1-r)^{t} [/tex]
Where,
a₀ is the original amount of the substance
a is the amount after time t.
r is the decay rate, written in decimals.
t is the time.
Transforming the given equation, we can write:
[tex]a=0.65(1-0.08)^{t}[/tex]
This means the decay rate for this radioactive element is 0.08 = 8%
Thus the percentage of decrease of the given radioactive element is 8%
