Basic math question

[ecb]

I have a question about figuring out prevalence - if there are 5 cases of a disease in 100,000 people, how many cases would be found in 1,000,000 people? thank you

 

[DrPhil]

I have a question about figuring out prevalence - if there are 5 cases of a disease in 100,000 people, how many cases would be found in 1,000,000 people? thank you

One way to do it is to set up a ratio: 5 is to 100,000 as X is to 1,000,000. Then solve for X.

Another way to see it is the fraction 5/(100,000) multiplied by 1,000,000.

Or just looking at the numbers: 1,000,000 is 10 times as many people as 100,000, so you would expect 10 times as many cases.