SOLUTION: The population of germs on a toilet seat doubles every 15 mins. How long to the nearest minute, would it take for the population to triple

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: The population of germs on a toilet seat doubles every 15 mins. How long to the nearest minute, would it take for the population to triple       Log On


   

Question 1171305: The population of germs on a toilet seat doubles every 15 mins. How long to the nearest minute, would it take for the population to triple
Found 2 solutions by Edwin McCravy, AnlytcPhil:
Answer by Edwin McCravy(20081) About Me  (Show Source):
Answer by AnlytcPhil(1810) About Me  (Show Source):
You can put this solution on YOUR website!
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:

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?
P=P%5B0%5De%5E%28r%2At%29

P0 = original population
P = the population after t minutes.

The population of germs on a toilet seat triples every 20 mins.
When P=20, P=3∙P0

Substitute in

3P%5B0%5D=P%5B0%5De%5E%28r%2A20%29

Divide both side by P0

3=e%5E%28r%2A20%29

Take natural logs of both sides:

ln%283%5E%22%22%29=ln%28e%5E%28r%2A20%29%29

ln%283%5E%22%22%29=r%2A20

ln%283%29%2F20=r

1.098612289%2F20=r

0.0549306144=r

Substitute in

P=P%5B0%5De%5E%280.0549306144%2At%29

P=P%5B0%5De%5E%280.0549306144%2At%29

How long to the nearest minute, would it take for the population to quadruple?
Substitute 

P=4∙P0

4%2AP%5B0%5D=P%5B0%5De%5E%280.0549306144%2At%29

Divide both side by P0

4=e%5E%280.0549306144%2At%29

Take natural logs of both sides:



ln%284%29%2F0.0549306144=t

25.23719016

To the nearest minute, every 25 minutes.

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

Edwin