Math  Algebra
posted by Mitchel
Need help understanding this problem. Looks like an exponential growth/decay.
Magnesium27 has a half life of 9.45 minutes and can be described by using the equation “y=ae^kt .
What is the decay constant (k) for Magnesium27?
How many mg of Magnesium27 will remain after 1.5 hours from an initial amount of 1000 mg?
How long will it take for 1000 mg of Magnesium to decrease to 780 mg?
Any explanation would be greatly appreciated!!

Steve
the amount halves every 9.45 minutes, so
y = a(1/2)^(t/9.45)
but,1/2 = e^0.693 so
y = a(e^0.693)^(t/9.45) = ae^(0.0733t)
where t is in minutes
Now use that to evaluate your other questions
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