Question

Find the half-life for a substance that decays by 7% each year.

Answer 1

y=a(1+(-7%))^t
let retriceume initial amount
R.A.I.X:100g
half = 50
y=a(1+(-0.07))^t
y=a(1+(0.93)^t
(50/100)=(100*(0.93))^t/(100)
(1/2)=(0.93)^t
( ln(1/2)/(ln(0.93)=t
(-0.693147)/(-0.072570)=t
t=9.56 years