# Stratified Sampling

how to work out a stratified sample

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• Created by: Kelly:)
• Created on: 01-06-11 16:32

## How to work out a Stratified Sample

just like working out a percentage you:

divide the number of the group you need a sample from by the total number of people and multiply the answer by the size of the sample you need to find.

for example:

There are 50 boys and 80 girls in a year group. You need to get a number of girls using a stratified sample of 30.

80/130 * 30 = 18.46153846

if you're unsure of which number to round it to, then find out the stratified sample of boys:

50/130 * 30 = 11.53846153

as this number is closer to 12, we would say the stratified sample of boys is 12 and the sample of girls is 18. 12 + 18 = 30 (just to prove you've got the right numbers)

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ahhh thank u soo much

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you're welcome! good luck with your exam :)

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thanks alot!! :)

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