SOLUTION: forty percent of a substance has decayed after 10 years. how much substance will remain after 15 years?

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Question 1050999: forty percent of a substance has decayed after 10 years. how much substance will remain after 15 years?
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
Q(t) = Q(0) e^kt
Q(t)/ Q(0) = e^kt
.40 = e^kt
ln(.4) = kt
ln(.4)/10 = k = -.0916
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Q(t)/Q(0)= e^(-.0916)15 = .253
25.3% left