# Bacteria doubling

• May 6th 2009, 12:17 PM
JohnBlaze
Bacteria doubling
I have a exponential function problem.

A population of 500 E. coli bacteria doubles every 15 minutes. Use this information to find an expression for this population growth. Using this expression, find what the population would be in 87 minutes. Use an exponential model.

I set up a table to find the values

time(15min) and population
0 500
15 1000
30 2000
45 4000
60 8000

I have to find the expression at 87mins.
The expression that I have is y=500e^x
I plug 87 in the equation for x and I end up getting 3.03 times 10 to the power of 40
I don't think I'm right.
Any help would be appreciated.
• May 6th 2009, 01:52 PM
skeeter
Quote:

Originally Posted by JohnBlaze
I have a exponential function problem.

A population of 500 E. coli bacteria doubles every 15 minutes. Use this information to find an expression for this population growth. Using this expression, find what the population would be in 87 minutes. Use an exponential model.

I set up a table to find the values

time(15min) and population
0 500
15 1000
30 2000
45 4000
60 8000

I have to find the expression at 87mins.
The expression that I have is y=500e^x
I plug 87 in the equation for x and I end up getting 3.03 times 10 to the power of 40
I don't think I'm right.
Any help would be appreciated.

try this equation ...

$P(t) = 500 \cdot 2^{\frac{t}{15}}$

t in minutes
• May 8th 2009, 05:37 PM
JohnBlaze
Quote:

Originally Posted by skeeter
try this equation ...

$P(t) = 500 \cdot 2^{\frac{t}{15}}$

t in minutes

Thanks a lot