SOLUTION: 1.Phosphorus-32 is used to study a plant's use of fertilizer. It has a half life of 14.3 days. Write the exponential decay function for a 50-mg sample. Find the amount of phosphoro

Algebra ->  Logarithm Solvers, Trainers and Word Problems -> SOLUTION: 1.Phosphorus-32 is used to study a plant's use of fertilizer. It has a half life of 14.3 days. Write the exponential decay function for a 50-mg sample. Find the amount of phosphoro      Log On


   

Question 136174: 1.Phosphorus-32 is used to study a plant's use of fertilizer. It has a half life of 14.3 days. Write the exponential decay function for a 50-mg sample. Find the amount of phosphorous- 32 remaining after 84 days?
2. Iodine-131 is used to find leaks in water pipes. It has a half life of 8.14 days. Write the exponential decay function for a 200-mg sample. Find the amount of iodine-131 remaining after 72 days.
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Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
The half-life decay formula:
:
A = Ao * 2^(-t/h)
Where:
A = resulting amount after t time
Ao = initial amount
t = elapsed time
h = half-life of the substance
:
1.Phosphorus-32 is used to study a plant's use of fertilizer. It has a half life of 14.3 days. Write the exponential decay function for a 50-mg sample. Find the amount of phosphorous- 32 remaining after 84 days?
:
A = 50 * 2^(-84/14.3)
:
A = 50 * 2^-5.874
:
A = 50 * .017; find 2^-5.874 on a good calculator
:
A = .8525 mg remain after 84 days
:
:
2. Iodine-131 is used to find leaks in water pipes. It has a half life of 8.14 days. Write the exponential decay function for a 200-mg sample. Find the amount of iodine-131 remaining after 72 day
:
Do this exactly the same way.
A = 200 * 2^(-72/8.14)
:
Do you have any questions?