# Math Help - Question about geometric series

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

4. Originally Posted by yida
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