To calculate the margin of error, we use the formula:
[tex]M_{\gamma}=z_{\gamma}\sqrt[]{\frac{\sigma^2}{n}}[/tex]So, we got n, the number of students, sigma, the standard deviation, and gamma, the confidence level. z for 95% is 1.64, so:
[tex]M_{95\text{ \%}}=1.64\sqrt[]{\frac{1400^2}{74}}=1.64\frac{1400}{\sqrt[]{74}}=266.9\approx267[/tex]So, the margin of error goes from mean - 267 to mean + 267:
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