the number N of bacteria in a culture is given by the model N= 100e^kt where t is the time in hours. If N=300 when t= 5, find the time required for the population to double in size.

Respuesta :

Answer:

It takes 3.15 hours for the population to double in size

Step-by-step explanation:

Given:

N= 100e^kt

N = 300

t  = 5

To Find:

The time required for the population to double in size

Solution:

Step 1: Finding the value of k

[tex]N= 100e^{kt}[/tex]-------------------(1)

ln(N) = ln(100) +kt

[tex]k = (\frac{1}{t})\cdot ln(\frac{N}{100})[/tex]

On substituting the given values

[tex]k = (\frac{1}{5})\cdot ln(\frac{300}{100})[/tex]

[tex]k = (\frac{1}{5})\cdot ln(3)[/tex]

[tex]k =(0.2)\cdot (1.098)[/tex]

k =  0.2197

Now eq(1) becomes

[tex]N= 100e^{(0.22)t}[/tex]-------------------(2)

Step 2: Finding t value

[tex]ln(N) = ln(100) \cdot (0.22)t[/tex]

[tex]t = (\frac{1}{0.22}) \cdot ln(\frac{N}{100})[/tex]

N= 200

[tex]t = (\frac{1}{0.22}) \cdot ln(\frac{200}{100})[/tex]

[tex]t = (\frac{1}{0.22}) \cdot ln(2)[/tex]

[tex]t = (4.54) \cdot(0.693)[/tex]

t = 3.15

The time required for the population to double in size is 3.15 hours.

Given data:

The linear model to represent the number of bacteria is,

[tex]N = 100e^{kt}[/tex] ........................................................(1)

Here, k is the constant and t is the time required for the population to double in size.

Linear model is a mathematical tool to determine the rate of decay of any substance with respect to time.

Take log on both sides of the linear model as,

[tex]ln(N) =ln( 100e^{kt})\\\\ln(N) =ln( 100)+kt \times ln(e)\\\\ln(N) =ln( 100)+kt\\\\k =\dfrac{1}{t} \times ln\dfrac{N}{100}[/tex]

If N=300 when t= 5. Then the equation is evaluated as,

[tex]k =\dfrac{1}{5} \times ln\dfrac{300}{100}\\\\k=0.2197[/tex]

For double size of population,

[tex]N = 2 \times 100 = 200[/tex]

Then solve by substituting all the values  in equation (1) as,

[tex]N = 100e^{kt}[/tex]

[tex](2 \times 100) = 100 \times e^{0.2197 \times t}\\200 = 100\times e^{0.2197 \times t}\\\\ln(2)= ln e^{0.2197 \times t}\\\\t = \dfrac{1}{0.2197} \times ln(2)\\\\t = 3.15 \;\rm hours[/tex]

Thus, the time required for the population to double in size is 3.15 hours.

Learn more about the linear model here:

https://brainly.com/question/24197246