SOLUTION: The half-life of Radium-226 is 1590 years. If a sample contains 300 mg, how many mg will remain after 4000 years?

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Question 978183: The half-life of Radium-226 is 1590 years. If a sample contains 300 mg, how many mg will remain after 4000 years?
Answer by Cromlix(4381) About Me  (Show Source):
You can put this solution on YOUR website!
Hi there,
After 1 half life of 1590 years 150mg of
original 300 mg will remain radioactive.
After 2 half lives of a total of 3180 years
(2 x 1590 yrs) 75 mg of the original 300 mg
will remain radioactive.
Now 4000 yrs - 3180 yrs = 820 yrs
820/1590 = 0.52
Therefore 0.52 of 75 mg = 38.7 mg
of the original 300mg will remain radioactive.
Hope this helps:-)