The number of bacteria in a Petri dish was initially determined to be 1. After one hour, the number of bacteria had increased to 3 and after another hour to 6. Assume that the rate of growth of bacteria in the dish at any time t can be calculated using the logistic equation

dB/dt =B(a-bB)

(a) Determine the number of bacteria in the dish after an additional hour has passed.

(b) Determine the carrying capacity of the dish based on the developed logistic equation.

Respuesta :

Answer:

a) the number of bacteria in the dish after an additional hour has passed = 8

b) the carrying capacity of the dish based on the developed logistic equation. = 9

Step-by-step explanation:

Given that ;

The Logistic growth model is :

[tex]\frac{dB}{dt}= B (a-bB)[/tex]

Solving the above equation  ; we have a MODEL EQUATION;

[tex]B_t = \frac{aB_o}{bB_o+(a-bB_o)e^{-at}}[/tex]

in which:

[tex]B_o[/tex] represents the initial population of the bateria.

We are given that the number of the bacteria in the Petri dish was initially determined to be 1 , then ;

[tex]B_t = \frac{a*1}{b*1+(a-b*1)e^{-at}}[/tex]

[tex]B_t = \frac{a}{b+(a-b)e^{-at}}[/tex]

After an hour ; we were told that the number of the bacteria increased to 3 ; So:

[tex]3 = \frac{a}{b+(a-b)e^{-a(1)}}[/tex]

[tex]3b+3(a-b)e^{-a} =a ---- equation (1)[/tex]

Similarly after (2) hours; the number of the bacteria increased to 6; then

[tex]6 = \frac{a}{b+(a-b)e^{-a(2)}}[/tex]

[tex]6b+6(a-b)e^{-2a} =a ---- equation (2)[/tex]

So;

[tex]3b+3(a-b)e^{-a} =a ---- equation (1)[/tex]

[tex]6b+6(a-b)e^{-2a} =a ---- equation (2)[/tex]

Solving for a and b from the above two eqautions: Then,

a = 1.386

b =  0.154

Substituting the value of a and b  into our MODEL EQUATION; we have

[tex]B_t = \frac{1.386}{0.154+(1.386-0.154*1)e^{-1.386t}}[/tex]

[tex]B_t = \frac{1.386}{0.154+1.232e^{-1.386t}}[/tex]

a)  Determine the number of bacteria in the dish after an additional hour has passed.

i.e at t = 3

[tex]B = \frac{1.386}{0.154+1.232e^{-1.386(3)}}[/tex]

[tex]B = \frac{1.386}{0.154+1.232 * 0.01563}[/tex]

[tex]B= \frac{1.386}{0.173267}[/tex]

[tex]B = 7.9992[/tex]

[tex]B= 8[/tex]

b) Determine the carrying capacity of the dish based on the developed logistic equation.

The carrying capacity B can be expressed as :

[tex]B = \frac{a}{b}[/tex]

[tex]B = \frac{1.386}{0.154}[/tex]

B =9