Question 364288
The half-life of radium is 1690 years. 
If 40 grams are present now, how much will be present in 400 years.
:
The half-life formula: A = Ao*2^(-t/h)
where
A = resulting amt after t yrs
Ao = initial amt
h = half-life of substance
t = time
:
We want to find A:
A= 40*2^(-400/1690) 
enter on a calc
A = 33.9477 grams after 400 yrs
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