Plutonium decays with a half - life of 24,000 years. If plutonium is stored for 72,000 years, what fraction of it remains ?

Explanation

Half life of plutonium, T = 24000 years, Stored time of plutonium, t = 72000 years
no. of half lives, `n = (t)/(T)=(72000)/(24000)=3`, Fraction of plutonium remains `=(N)/(N_(0))=(1)/(2^(n))=(1)/(2^(3))=(1)/(8)`