Plutonium,
239Pu, has a half-life of 24,100 years. What percent of a given amount remains after 100,000 years?
Is this done correctly?
k=0.00002876
= 56.35% after 100,000 years
Half-life = ln(2)/lambda
This gives lambda = 2.876*10^(-5)
Then N = N0*e^(-lambda*t)
Set N0 = 100% gives you:
100*e^(-2.876*10^-5*100000) = 5.9%
Sounds right 50;25;12.5;6.25 = 4 halflifes and gives you about 6% left
ops: Too slow, evenwithout this latex =)