A margin of error gives a limit on how much the responses of a sample would differ from the responses of the population. If we let n be the size of a random sample taken from a large population, we can write an expression for the margin of error.
Margin of Error: ± 1/sqrt(n)
We are told that a survey has a sample size n equal to 750. Let's find the margin of error by substituting this value in the above expression.
Margin of Error: ± 1/sqrt(750) ≈ ± 0.037
The margin of error for the survey is about ± 0.037, which can be also written as ± 3.7 %.
