Question 1171305
<pre>
Instead of doing your problem for you, I'll do a different one that is done
exactly the same way, step by step.

I'll do this one:
</pre>
The population of germs on a toilet seat triples every 20 mins. How long to the nearest minute, would it take for the population to quadruple?
<pre>
{{{P=P[0]e^(r*t)}}}

P<sub>0</sub> = original population
P = the population after t minutes.
</pre>
The population of germs on a toilet seat triples every 20 mins.
<pre>
When P=20, P=3∙P<sub>0</sub>

Substitute in

{{{3P[0]=P[0]e^(r*20)}}}

Divide both side by P<sub>0</sub>

{{{3=e^(r*20)}}}

Take natural logs of both sides:

{{{ln(3^"")=ln(e^(r*20))}}}

{{{ln(3^"")=r*20}}}

{{{ln(3)/20=r}}}

{{{1.098612289/20=r}}}

{{{0.0549306144=r}}}

Substitute in

{{{P=P[0]e^(0.0549306144*t)}}}

{{{P=P[0]e^(0.0549306144*t)}}}
</pre>
How long to the nearest minute, would it take for the population to quadruple?
<pre>
Substitute 

P=4∙P<sub>0</sub>

{{{4*P[0]=P[0]e^(0.0549306144*t)}}}

Divide both side by P<sub>0</sub>

{{{4=e^(0.0549306144*t)}}}

Take natural logs of both sides:

{{{ln(4^"")=ln(e^(0.0549306144*t))

{{{ln(4^"")=0.0549306144*t}}}

{{{ln(4)/0.0549306144=t}}}

{{{25.23719016}}}

To the nearest minute, every 25 minutes.

Now do yours exactly the same way, step by step.

Edwin</pre>