Answer:
![D =\frac{P}{\pi X^2}](https://tex.z-dn.net/?f=%20D%20%3D%5Cfrac%7BP%7D%7B%5Cpi%20X%5E2%7D)
And solving for the radius we got:
![X = \sqrt{\frac{P}{\pi D}}](https://tex.z-dn.net/?f=%20X%20%3D%20%5Csqrt%7B%5Cfrac%7BP%7D%7B%5Cpi%20D%7D%7D)
And replacing the data given we got:
![X = \sqrt{\frac{480 \frac{people}{km^2}}{\pi *20000 people}}= 0.0874Km](https://tex.z-dn.net/?f=%20X%20%3D%20%5Csqrt%7B%5Cfrac%7B480%20%5Cfrac%7Bpeople%7D%7Bkm%5E2%7D%7D%7B%5Cpi%20%2A20000%20people%7D%7D%3D%200.0874Km)
And this value converted to meters is ![X = 87.40 m](https://tex.z-dn.net/?f=X%20%3D%2087.40%20m)
Step-by-step explanation:
For this case we know the population size
and we also know the population density ![D = 480 \frac{people}{km^2}](https://tex.z-dn.net/?f=%20D%20%3D%20480%20%5Cfrac%7Bpeople%7D%7Bkm%5E2%7D)
We can assume that the area is a circle. We also know that the formula for the population density is given by:
![D= \frac{P}{A}](https://tex.z-dn.net/?f=%20D%3D%20%5Cfrac%7BP%7D%7BA%7D)
Where P represent the number of people and A the area. Since we are assuming a circle then the area is given by:
![A = \pi X^2](https://tex.z-dn.net/?f=%20A%20%3D%20%5Cpi%20X%5E2)
With X the radius of the circle
And then the populationd density become:
![D =\frac{P}{\pi X^2}](https://tex.z-dn.net/?f=%20D%20%3D%5Cfrac%7BP%7D%7B%5Cpi%20X%5E2%7D)
And solving for the radius we got:
![X = \sqrt{\frac{P}{\pi D}}](https://tex.z-dn.net/?f=%20X%20%3D%20%5Csqrt%7B%5Cfrac%7BP%7D%7B%5Cpi%20D%7D%7D)
And replacing the data given we got:
![X = \sqrt{\frac{480 \frac{people}{km^2}}{\pi *20000 people}}= 0.0874Km](https://tex.z-dn.net/?f=%20X%20%3D%20%5Csqrt%7B%5Cfrac%7B480%20%5Cfrac%7Bpeople%7D%7Bkm%5E2%7D%7D%7B%5Cpi%20%2A20000%20people%7D%7D%3D%200.0874Km)
And this value converted to meters is ![X = 87.40 m](https://tex.z-dn.net/?f=X%20%3D%2087.40%20m)
Answer
215 can only be divided by 5
Combine the fractions by finding a common denominator.
10r+9/r(r+3)