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### 15.27

Posted: Sat Mar 03, 2018 4:43 pm
How do you calculate the time it takes for something to get to 15% of its initial concetration and 1/9th of its initial condition if you are given only its half life?

### Re: 15.27

Posted: Sat Mar 03, 2018 5:27 pm
You can assume that the initial concentration equals 1 and the final concentration you're looking for equals 0.15 when solving the half-life equation for time.

### Re: 15.27

Posted: Sat Mar 03, 2018 5:33 pm
Using the given half-life, we can use the formula $k=\frac{0.693}{t_{1/2}}$ to calculate the k value. From there, we can use the formula $ln[A]_{t}=ln[A]_{0}-kt$ to calculate time. [A]t is the concentration remaining after time t.