# Math Help - [SOLVED] natural log

1. ## [SOLVED] natural log

$P=130e^{-.000155h}$
find h when P = 8.5

$8.5=130e^{-.000155h}$

I take LN of both sides then solve for h but I get -2353?

2. Originally Posted by brentwoodbc
$P=130e^{-.000155h}$
find h when P = 8.5

$8.5=130e^{-.000155h}$

I take LN of both sides then solve for h but I get -2353?
What steps did you do? Mine are below to check against

$e^{-0.000155h} = 8.5/130$

take natural logs:

$-0.000155h = ln{(\frac{8.5}{130})}$

$h = \frac{1}{-0.000155}\cdot ln{(\frac{8.5}{130})} = 17600 (3sf)$

3. k I got It, I was typing it into my calculator wrong, thanks again