Calculating amounts

Question

Greetings, if you have 144 people per 10,000 with an illness. How many people would that be for 260 million people. I just want to understand the calculation. I did it a couple of different ways, and I just don't feel confident of the answer..Any help would be appreciated.

Answer 1

You could set up a proportion:

144/10000 = x / (260x10⁶)

then solve for x.

An alternate (and equivalent) method is to compute the illness rate ("illnesses per person"): R = 144 / 10000. Then you can use R * 260x10⁶ to get the number of illnesses expected (3744000) for the specific population.

Answer 2

This is a ratio problem:

144/10,000 = x/260,000,000

One way to solve for x is to "cross-multiply".

This gives

144 * 260,000,000 = 10,000 x

Divide both sides by 10,000 gives

3,744,000 = x