The fourth one, (3,-6), (3,-4), (6,-4), (6,-6)
The population of the Bulbul birds at the start of the migration season is 1800.
<h3>
Exponential function</h3>
An exponential function is given by:
y = abˣ
Let y, x are variables, a is the initial value and b is the multiplication factor.
Let P be the population of the bird t days since the start of the migration season.

The population of the Bulbul birds at the start of the migration season is 1800.
Find out more on Exponential function at: brainly.com/question/12940982
The formula for a right cone:
V = πr^2(h/3)
V: Volume
r: radius
h: height
πr^2 = base area of a cone
Answer
The formula for the volume in terms of base area b and height h is: V = b(h/3)
Let's look at the picture, let's imagine that the gray line is the perimeter fence and that the red OR the blue is the one dividing it. We can see that the blue line is longer than the red one, so it will be advantageous, to have a bigger area, to have the dividing fence the smallest possible.
Let's say then that the width (W) is bigger (or equal) to the length (L), so we have:

The area is W*L, so we have

this function is a parabola facing down, its zeros are 0 and 80, therefore its maximum is when L=40
hence, L=40 and W=(240-120)/2=60
It will be a rectangle, measuring 60x40 and the divinding fence will be 40