A scientist is studying some rabbits. A disease is killing the rabbits. A population of 240 of these rabbits was reduced to 180 rabbits in two days. The rabbit population is decreasing exponentially. Work out how many of the 240 rabbits will still be alive at the end of 7 days (5 marks)

Respuesta :

Here we have a problem with exponential decays,  we will find that we can expect that 110 rabbits will still be alive at the end of 7 days.

An exponential decay can be written:

P(x) = A*e^(-k*x)

Where:

A is the initial amount.

k defines the rate of decrease.

x is our variable.

In this case, the exponential decay is applied to the population of rabbits, and we know that:

The initial population is 240, then A = 240

P(x) = 240*e^(-k*x)

We also know that after two days (at x = 2) the population was 180, then we can write:

P(2) = 180 = 240*e^(-k*2)

With this equation we can find the value of k:

180 = 240*e^(-k*2)

180/240 = e^(-k*2)

Now remember that:

Ln(e^n) = n

then if we apply the natural logarithm to both sides, we get:

Ln(180/240) = Ln(e^(-k*2)) = -k*2

-Ln(180/240)/2 = k = 0.144

Then the equation is:

P(x) = 240*e^(-0.144*x)

Now with this, we can find the population of rabbits after 7 days, we just need to evaluate the above function at x = 7, we will get:

P(7) = 240*e^(-0.144*7) = 110.3

That we could round down to the next whole number, 110.

Concluding, we can expect that 110 rabbits will still be alive at the end of 7 days.

If you want to learn more, you can read:

https://brainly.com/question/14355665

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