What is 3x + (2- 4x)

The Department of Agriculture is monitoring the spread of mice by placing 100 mice at the start of the project. The population,

uranmaximum [27]

Answer:

Step-by-step explanation:

Assuming that the differential equation is

$\frac{dP}{dt} = 0.04P\left(1-\frac{P}{500}\right)$ .

We need to solve it and obtain an expression for $P(t)$ in order to complete the exercise.

First of all, this is an example of the logistic equation, which has the general form

$\frac{dP}{dt} = kP\left(1-\frac{P}{K}\right)$ .

In order to make the calculation easier we are going to solve the general equation, and later substitute the values of the constants, notice that $k=0.04$ and $K=500$ and the initial condition $P(0)=100$ .

Notice that this equation is separable, then

$\frac{dP}{P(1-P/K)} = kdt$ .

Now, intagrating in both sides of the equation

$\int\frac{dP}{P(1-P/K)} = \int kdt = kt +C$ .

In order to calculate the integral in the left hand side we make a partial fraction decomposition:

$\frac{1}{P(1-P/K)} = \frac{1}{P} - \frac{1}{K-P}$ .

So,

$\int\frac{dP}{P(1-P/K)} = \ln|P| - \ln|K-P| = \ln\left| \frac{P}{K-P} \right| = -\ln\left| \frac{K-P}{P} \right|$ .

We have obtained that:

$-\ln\left| \frac{K-P}{P}\right| = kt +C$

which is equivalent to

$\ln\left| \frac{K-P}{P}\right|= -kt -C$

Taking exponentials in both hands:

$\left| \frac{K-P}{P}\right| = e^{-kt -C}$

Hence,

$\frac{K-P(t)}{P(t)} = Ae^{-kt}$ .

The next step is to substitute the given values in the statement of the problem:

$\frac{500-P(t)}{P(t)} = Ae^{-0.04t}$ .

We calculate the value of $A$ using the initial condition $P(0)=100$ , substituting $t=0$ :

$\frac{500-100}{100} = A}$ and $A=4$ .

So,

$\frac{500-P(t)}{P(t)} = 4e^{-0.04t}$ .

Finally, as we want the value of $t$ such that $P(t)=200$ , we substitute this last value into the above equation. Thus,

$\frac{500-200}{200} = 4e^{-0.04t}$ .

This is equivalent to $\frac{3}{8} = e^{-0.04t}$ . Taking logarithms we get $\ln\frac{3}{8} = -0.04t$ . Then,

$t = \frac{\ln\frac{3}{8}}{-0.04} \approx 24.520731325$ .

So, the population of rats will be 200 after 25 months.

6 0

4 years ago

A distribution has a mean of 16 and a standard deviation of 6. What is the Z score that corresponds with 34?

Brrunno [24]

Answer:

Z = 3

Step-by-step explanation:

In a normal distribution, the Z score that corresponds with a data point x is calculated using the formula;

$Z=\frac{x-mean}{standard deviation}$

For the case given, the z score will be;

$Z=\frac{34-16}{6}=3$

7 0

4 years ago

Jamie Earns 10% commission on her sales after she has sold a minimum of $2000 each month for the lippy cosmetics company, last m

Licemer1 [7]

I'm sorry but I do not understand your question. It is not specified what you are looking for.

7 0

3 years ago

An 8×8×8 cm cube was painted red, and then broken up into small cubes with side lengths of 1 cm. How many small cubes have none

Alona [7]

Answer:

216

Step-by-step explanation:

If you just paint the surface of the cube, then the inside of the cube would not have any of their faces painted red.

Just looking at the cube from a side view, you would realize that there would be a smaller cube, 6 x 6 x 6 (not 7 since you have to account for both the top side and the bottom side), and so that is the answer, 6 ^ 3, which is 216.

8 0

3 years ago

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What is the slope of the line that passes through the points (6, 2) and (4, 10)?

drek231 [11]

Answer:

-4

Step-by-step explanation:

Slope = y2 - y1/x2 - x1

Given

x1 = 6

y1 = 2

x2 = 4

y2 = 10

Therefore

Slope = 10 - 2/4 - 6

= 8/-2

= -4

5 0

3 years ago

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