SOLUTION: Potassium 42 has a decay rate of approximately 5.5% per hour, assuming an exponential decay model, fine the number of hours it will take for the original quantity of potassium 42 t

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: Potassium 42 has a decay rate of approximately 5.5% per hour, assuming an exponential decay model, fine the number of hours it will take for the original quantity of potassium 42 t      Log On


   



Question 566011: Potassium 42 has a decay rate of approximately 5.5% per hour, assuming an exponential decay model, fine the number of hours it will take for the original quantity of potassium 42 to b halved?
Found 2 solutions by stanbon, KMST:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Potassium 42 has a decay rate of approximately 5.5% per hour, assuming an exponential decay model, find the number of hours it will take for the original quantity of potassium 42 to b halved?
----
y = ab^x
---
(1/2)a = a*b^x
---
1/2 = b^x
---
1/2 = 0.945^x
x = log(1/2)/log(0.945)
--
x = 12.25 years
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Cheers,
Stan H.
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Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
The decay function could be represented as
fraction remaining remaining=e%5E%28-kt%29
With t in hours, we know that at t=1, fraction remaining=1-0.055=0.945
0.945=e%5E%28-k%29 <---> ln%280.945%29=-k
We want to find t so that 50% is left, so
0.5=e%5E%28-kt%29 <---> ln%280.5%29=-kt
Combining both equations
ln%280.5%29%2Fln%280.945%29=t
t=12.25