SOLUTION: The amount of a radioactive tracer after t days is given by A=A lower case o e^-0.18t, where A is the starting amount at the beginning of the time period. How much should be acquir

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Question 95228This question is from textbook Algebra and Trigonometry
: The amount of a radioactive tracer after t days is given by A=A lower case o e^-0.18t, where A is the starting amount at the beginning of the time period. How much should be acquired now to have 40 grams remaining after 3 days? This question is from textbook Algebra and Trigonometry

Found 2 solutions by stanbon, ankor@dixie-net.com:
Answer by stanbon(75887) (Show Source):
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The amount of a radioactive tracer after t days is given by A(t)=Aoe^-0.18t, where A is the starting amount at the beginning of the time period. How much should be acquired now to have 40 grams remaining after 3 days?
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Let A(3) = 40 grams and solve for Ao
40=Aoe^-0.18t
40/e^-0.18(3) = Ao
Ao = 40/0.582748...
Ao = 68.64... grams is how much you would have to start with.
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Cheers,
stan H.

Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website!
The amount of a radioactive tracer after t days is given by A =A lower case o e^-0.18t, where A is the starting amount at the beginning of the time period. How much should be acquired now to have 40 grams remaining after 3 days?
:
Actually, I think they mean the starting amt is Ao, and
A is the amt after t days.
:
= A
:
Substitute 40 for A and 3 for t in the above equation:
= 40
:
= 40
:
Find on a good calc
.58275Ao = 40
Ao =
Ao = 68.64 grams, is the initial amt to have 40 grams in 3 days
:
:
Check on a calc: enter: 68.64 * e^-.54 = 39.9998 ~ 40