You can put this solution on YOUR website! A substance has a half life of 23 hours .
How old is the object that has 5% of the substance left?
:
The radioactive decay formula:
A = Ao*2^(-t/h), where
A = resulting amt after t
Ao = initial amt (t-0)
t = time of decay
h = half-life of substance
:
Let initial amt = 1, then we can write the equation
1*2^(-t/23) = .05
Using nat logs and the log equiv of exponents =
: = -4.3219
multiply both sides by -23
:
:
You can check this on a good calc: enter: 2^(-99.4/23), results: .05 which is 5%
t = 99.4 days to a 5% remaining
