1. ## Question about geometric series

I don't quite understand half-life. How to solve this question?

2. Originally Posted by yida
I don't quite understand half-life. How to solve this question?
$y = y_0\left(\frac{1}{2}\right)^{\frac{t}{h}}$

$y$ = amount left at any time $t$ in hrs

$y_0$ = amount at $t = 0$

$h$ = half-life in hrs

3. the answer is wrong

4. Originally Posted by yida
the answer is wrong
what answer are you speaking of ?

I gave you the general function for half-life, not an "answer".

5. I use y0=55
t=12 h=7.2
but I got wrong answer

6. what "wrong answer" did you get?

7. 55(0.5)^(12/7.2)

8. Originally Posted by yida
55(0.5)^(12/7.2) = 17.324 mg
... and that is not wrong.