how can I find out what 100% of population is when I only know what 70% of population is?

Answer 1

You can make a ratio and cross-multiply.

For example, if I know that 70% of the population is 250, then I'd set up the ratio like this:

250/70 = x/100

Cross-multiplying means you'd multiply 250 by 100 and 70 by x

70x = 25000

Now divide both sides by 70, and you'll find out what x is.