## Quick Logarithm Homework Check

For the discussion of math. Duh.

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Assasinof6
Posts: 22
Joined: Sun May 09, 2010 1:37 pm UTC

### Quick Logarithm Homework Check

Pretty much what the title says. I'm trying to solve for "t" in this scenario.
P(t) = Percentage of C-14 Remaining = 70
t = time

P(t) = 100(1/2)^(t/5730)

P(t)/100 = (1/2)^(t/5730)
(logP(t))/100 = log(1/2)^(t/5730)

(log(P(t))/100 = (t/5730)log(1/2)

((log(P(t))(log(1/2)))/573000 = t

t= ((log(70))(log(1/2)))/573000

t = -9.69 x 10^-7

I'm pretty sure it's wrong. I know it looks confusing like this, but if you write it out you'll probably see where I went wrong... I hope!

Thanks!
I see.
What?
That you don't.

joshz
Posts: 1466
Joined: Tue Nov 11, 2008 2:51 am UTC
Location: Pittsburgh, PA

### Re: Quick Logarithm Homework Check

Assasinof6 wrote:P(t)/100 = (1/2)^(t/5730)
(logP(t))/100 = log(1/2)^(t/5730)
Why didn't you take the log of 100? That line should be
$log \frac {P(t)}{100} = log((1/2)^{t/5730})$
You, sir, name? wrote:If you have over 26 levels of nesting, you've got bigger problems ... than variable naming.
suffer-cait wrote:it might also be interesting to note here that i don't like 5 fingers. they feel too bulky.

Assasinof6
Posts: 22
Joined: Sun May 09, 2010 1:37 pm UTC

### Re: Quick Logarithm Homework Check

Thanks! I got the right answer after continuing to solve from there.
Much appreciated.
I see.
What?
That you don't.