SOLUTION: How do I set-up/solve this problem? Please help me. The half-life of the radioactive isotope gallium-70 is 20 minutes. If the initial amount of gallium-70 is 25 milligrams, when

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Question 410680: How do I set-up/solve this problem? Please help me.
The half-life of the radioactive isotope gallium-70 is 20 minutes. If the initial amount of gallium-70 is 25 milligrams, when will 10 milligrams be left?
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
(amount remaining) = (starting amount)[(1/2)^(t/h)] ___ where t is the elapsed time and h is the half life

log(R) = log(S) + [(t/h)log(1/2)]

[log(R) - log(S)] / log(1/2) = t / h