SOLUTION: A certain radioactive substance has a half-life of 400 years. If 60 kg is accidently released when will 0.25 kg remain? (assumming it decays continuously) Please help me with t

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: A certain radioactive substance has a half-life of 400 years. If 60 kg is accidently released when will 0.25 kg remain? (assumming it decays continuously) Please help me with t      Log On


   

Question 526590: A certain radioactive substance has a half-life of 400 years. If 60 kg is accidently released when will 0.25 kg remain? (assumming it decays continuously)
Please help me with this one, I'm not even sure where to start! Don't you just love the assignments we get before we actually learn the material!! I hate to ask for help, but I have no idea how to set this up and calculate it!
Thank you,
Tracy
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
the general formula for half-life decay is ___ A = Ao [.5^(t / h)]

A = amount after decay
Ao = starting amount
t = time
h = half-life

ln(A / Ao) = (t / h)[ln(.5)] ___ h[ln(A / Ao)] / [ln(.5)] = t