What is the formula #("group size")/("total population")times"sample size"# used for?

1 Answer
Zor Shekhtman
Oct 18, 2015

To find (approximately!) the number of members of a particular group among all in a sample.

Explanation:

Assume, you know that 180 million of people (group size) out of 300 million who live in the United States (total population) are either working or actively looking for a job.

If you randomly choose a city with a population of 3 million people (sample), how many of them (approximately!) are working or actively looking for a job?

An answer is:

#180000000/300000000*3000000 = 1800000#

So, you count on (approximately!) 1.8 million people working or actively looking for a job in this city.

Related questions
Impact of this question
2001 views around the world
You can reuse this answer
Creative Commons License