Answer:
8.55 days for a decay rate parameter of 8.1% per day
Step-by-step explanation:
Assuming a decay rate parameter of  8.1% per day
the general equation for radioactive decay is;
N = N₀e^(-λt)
x - decay constant (λ) - rate of decayÂ
t- Â timeÂ
N - amount remaining after t days , since we are calculating the half life, amount of time it takes for the substance to to be half its original value, its N₀/2
Nâ‚€ - amount initially presentÂ
substituting the valuesÂ
Nâ‚€/2 =Â Nâ‚€e^(-0.081t)
0.5 =Â e^(-0.081t)
ln (0.5) = -0.081t
-0.693 = -0.081t
t = 0.693 / 0.081 Â = 8.55
half life of substance is 8.55 daysÂ