Sample size needed
If you want to calculate a confidence interval for the population mean with a certain margin of error, you can figure out the sample size you need before you collect any data. The formula for the sample size for
\[\vec{X} \]
where z* is the standard normal value for the confidence level, MOE is your desired margin of error, and
\[ \vec{X} \]
is the standard deviation
\[n= \left ( \frac {z*\sigma }{MOE} \right )^{2}\]
for calculation let value o f MOF=m