Margin of error
The question
625 fans were asked about the match. What is the margin of error?
One over the square root of how many were asked
n=625
√625=25
1 ÷ 25=4%
4%
- 625 people were asked. The margin of error depends on that number and nothing else — not on what they said, and not on how big the country is.
- Take the square root first: 25 × 25 = 625, so √625 is 25.
- Then one over it, as a percent: 1 ÷ 25 = 4%.
- So the margin of error is about 4%. Because of the square root, halving it would take four times as many people.
How it works.
- 01
625 people were asked. The margin of error depends on that number and nothing else — not on what they said, and not on how big the country is.
- 02
Take the square root first: 25 × 25 = 625, so √625 is 25.
- 03
Then one over it, as a percent: 1 ÷ 25 = 4%.
- 04
So the margin of error is about 4%. Because of the square root, halving it would take four times as many people.