We are given the population of Australia and its area. To calculate the number of people per square mile we simply divide as follows

To calculate this number, first we use the following property

So

Then, we have

Note that 2.15 = 215/100 and 2.95=295/100. So we have

Using the property

we get

Using a calculator we get

so the approximate average number of people per square mile in Australia is 7.28 people per square mile