The populations of two cultures of bacteria, A and B, after x hours are shown below. Which statement is a correct comparison of bacteria A and bacteria B?

Sagot :

Answer:

(c)

Step-by-step explanation:

Given

See attachment for A and B

Required

Compare A and B

First, we get the initial population of A and B.

The initial population is at when [tex]t =0[/tex]

From the table of bacteria A, we have:

[tex]Initial = 100[/tex] when [tex]t = 0[/tex]

From the graph of bacteria B, we have:

[tex]Initial = 75[/tex] when [tex]t = 0[/tex]

Since the initial of bacteria B is less than that of bacteria A, then (a) is incorrect.

Next, calculate the slope of A and B i.e. the rate

Slope (m) is calculated as:

[tex]m = \frac{y_2 - y_1}{t_2 - t_1}[/tex]

Where

y = Number of bacteria

t = time

For bacteria A:

[tex](t_1,y_1) = (0,100)[/tex]

[tex](t_2,y_2) = (2,140)[/tex]

So, the slope is:

[tex]m_A = \frac{140 - 100}{2 - 0}[/tex]

[tex]m_A = \frac{40}{2}[/tex]

[tex]m_A = 20[/tex]

For bacteria B:

[tex](t_1,y_1) = (0,75)[/tex]

[tex](t_2,y_2) = (1,100)[/tex]

So, the slope is:

[tex]m_B = \frac{100- 75}{1 - 0}[/tex]

[tex]m_B = \frac{25}{1 }[/tex]

[tex]m_B = 25[/tex]

Since [tex]m_B > m_A[/tex], then the rate of bacteria B is greater than that of bacteria A.

Hence, (d) cannot be true

Next, we determine the equation of both bacteria

This is calculated using:

[tex]y = m(t - t_1) + y_1[/tex]

For bacteria A, we have:

[tex]y = m_A(t - t_1) + y_1[/tex]

Where:

[tex](t_1,y_1) = (0,100)[/tex]

[tex]m_A = 20[/tex]

So:

[tex]y = 20(t - 0) +100[/tex]

[tex]y = 20(t) +100[/tex]

[tex]y = 20t +100[/tex]

For bacteria B, we have:

[tex]y = m_B(t - t_1) + y_1[/tex]

Where:

[tex](t_1,y_1) = (0,75)[/tex]

[tex]m_B = 25[/tex]

So:

[tex]y = 25(t - 0) + 75[/tex]

[tex]y = 25(t) + 75[/tex]

[tex]y = 25t + 75[/tex]

At 3 hours, the population of bacteria A is:

[tex]y = 20t +100[/tex]

[tex]y = 20* 3 + 100[/tex]

[tex]y = 60 + 100[/tex]

[tex]y = 160[/tex]

At 3 hours, the population of bacteria B is:

[tex]y = 25t + 75[/tex]

[tex]y=25 * 3 + 75[/tex]

[tex]y=75 + 75[/tex]

[tex]y=150[/tex]

After 3 hours, bacteria B is 150 while A is 160.

This implies that (c) is correct because the population of B is less than that of A, at 3 hour

Lastly, to check if they will ever have equal population or not, we simply equate both equations.

So, we have:

[tex]y = y[/tex]

[tex]25t + 75 =20t + 100[/tex]

Collect like terms

[tex]25t - 20t = 100 - 75[/tex]

[tex]5t = 25[/tex]

Solve for t

[tex]t = 25/5[/tex]

[tex]t = 5[/tex]

They will have equal population at 5 hours.

Hence, b is incorrect

From the above computation, only (c) is correct

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