Finding initial population....

In summary: So, in summary, the initial population is $P_0=2455$ and the population increases by 2455 each unit of time.
  • #1
rayne1
32
0
Assume the population of bacteria in a culture increases at a rate proportional to the current population. The population increased by 2455 from t = 2 to t = 3 and by 4314 from t = 4 to t =5. Find the initial population and how many times does the population increase each unit of time?

I don't really understand what I'm supposed to do.
 
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  • #2
We know the population will take the form:

\(\displaystyle P(t)=P_0e^{kt}\)

We are then given:

\(\displaystyle P(3)-P(2)=2455\)

\(\displaystyle P(5)-P(4)=4314\)

This will give you 2 equations and 2 unknowns...can you proceed to find the initial population $P_0$?
 
  • #3
MarkFL said:
We know the population will take the form:

\(\displaystyle P(t)=P_0e^{kt}\)

We are then given:

\(\displaystyle P(3)-P(2)=2455\)

\(\displaystyle P(5)-P(4)=4314\)

This will give you 2 equations and 2 unknowns...can you proceed to find the initial population $P_0$?

What would be the k value?
 
  • #4
rayne said:
What would be the k value?

This would also have to be algebraically determined. Let's look at the first equation I gave:

\(\displaystyle P(3)-P(2)=2455\)

This then becomes (using the definition of $P(t)$):

\(\displaystyle P_0e^{3k}-P_0e^{2k}=2455\)

Now, if we factor on the left, we obtain:

\(\displaystyle P_0e^{2k}\left(e^k-1\right)=2455\)

And solving for $P_0$ we then get:

\(\displaystyle P_0=\frac{2455}{e^{2k}\left(e^k-1\right)}\)

Now, if we state the second equation I gave, we have (after factoring):

\(\displaystyle P_0e^{4k}\left(e^k-1\right)=4314\)

At this point we may substitute for $P_0$ that we obtained above:

\(\displaystyle \frac{2455}{e^{2k}\left(e^k-1\right)}e^{4k}\left(e^k-1\right)=4314\)

Now you may simplify, then solve for $e^k$, and then you can determine $P_0$.
 
  • #5
MarkFL said:
This would also have to be algebraically determined. Let's look at the first equation I gave:

\(\displaystyle P(3)-P(2)=2455\)

This then becomes (using the definition of $P(t)$):

\(\displaystyle P_0e^{3k}-P_0e^{2k}=2455\)

Now, if we factor on the left, we obtain:

\(\displaystyle P_0e^{2k}\left(e^k-1\right)=2455\)

And solving for $P_0$ we then get:

\(\displaystyle P_0=\frac{2455}{e^{2k}\left(e^k-1\right)}\)

Now, if we state the second equation I gave, we have (after factoring):

\(\displaystyle P_0e^{4k}\left(e^k-1\right)=4314\)

At this point we may substitute for $P_0$ that we obtained above:

\(\displaystyle \frac{2455}{e^{2k}\left(e^k-1\right)}e^{4k}\left(e^k-1\right)=4314\)

Now you may simplify, then solve for $e^k$, and then you can determine $P_0$.

Oh, thank you! I got a bit lazy to try everything out.
 

Related to Finding initial population....

1. What is the significance of finding the initial population?

Finding the initial population is important because it serves as the starting point for studying a population and understanding its characteristics and trends over time.

2. How is the initial population determined?

The initial population can be determined through various methods, such as census data, historical records, or scientific surveys. It is important to use reliable and accurate data sources for obtaining the initial population.

3. What factors can affect the initial population?

Several factors can affect the initial population, including birth and death rates, immigration and emigration, natural disasters, and human activities such as hunting or deforestation. It is important to consider these factors when determining the initial population.

4. Why is it important to estimate the initial population accurately?

Estimating the initial population accurately is crucial for making informed decisions and predictions about the population's future growth and sustainability. It also helps in understanding the impact of various factors on the population and implementing effective management strategies.

5. Can the initial population change over time?

Yes, the initial population can change over time due to various factors such as population growth, environmental changes, and human activities. It is important to regularly update and re-evaluate the initial population to accurately track and manage the population's changes.

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