# Math Help - Radio-active decay problem.

I have the following equation.

$N/6= N*exp(-.0001216t)$

Then I want to solve to t, and the solution is $ln(6)/.00001216$

I must be missing something....why is $ln(6)$ and not $ln(1/6)$?

2. Originally Posted by tactical
I have the following equation.

$N/6= N*exp(-.0001216t)$

Then I want to solve to t, and the solution is $ln(6)/.00001216$

I must be missing something....why is $ln(6)$ and not $ln(1/6)$?
$N/6= N*exp(-.0001216t)$

$1/6= exp(-.0001216t)$

$6= exp(0.0001216t)$

$\ln 6= (0.0001216t)$

$t = \frac{\ln 6}{0.0001216}$

3. Originally Posted by tactical
I have the following equation.

$N/6= N*exp(-.0001216t)$

Then I want to solve to t, and the solution is $ln(6)/.00001216$

I must be missing something....why is $ln(6)$ and not $ln(1/6)$?
You could also write the answer as t= ln(1/6)/(-.0001216). Now ln(1/6)= -ln(6).