# Thread: exponential decay of a mixture

1. ## exponential decay of a mixture

I have some stuff that decays exponentially. The problem is I have a vat of a mixture of the stuff, all added at different times. I can measure the level remaining at a given time. How do I calculate the half life? I get this equation:
$Level=Q1*0.5^\frac{time1}h+Q2*0.5^\frac{time2}h$...
and hit a wall. Any help would be greatly appreciated.

2. Originally Posted by notamathguy
I have some stuff that decays exponentially. The problem is I have a vat of a mixture of the stuff, all added at different times. I can measure the level remaining at a given time. How do I calculate the half life? I get this equation:
$Level=Q1*0.5^\frac{time1}h+Q2*0.5^\frac{time2}h$...
and hit a wall. Any help would be greatly appreciated.
Please provide the exact text of and instructions for the exercise in question, so we can be clear on what is meant. Thank you!

3. Sorry, it's not an exercise, it's a real world problem. To treat hemophilia we inject a protein into our bloodstream. This clotting factor has a half life that varies by individual. Each dose decays at the same rate, but each has its own time period and initial quantity (the Q in my equation). So, the actual level at any time is given by the sum of each remaining dose. The problem is to determine what half life will produce the measured level 'L' at 'T' if I know the times and quantities for each dose.

4. Hi guys,
Lots of people have read this thread. Is this the wrong place to ask this question, is my explanation bad, or is there just no good solution?

Dan

5. Originally Posted by notamathguy
Hi guys,
Lots of people have read this thread. Is this the wrong place to ask this question, is my explanation bad, or is there just no good solution?

Dan
I can't answer the original question but I can quote from the thread http://www.mathhelpforum.com/math-he...ing-faq-2.html:

Why doesn’t anyone respond to my question?
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