Question

If the population standard deviation is 10 , how large a sample is necessary to have a standard error that is

Answer 1

The standard error given a population standard deviation of
`\sigma` is
`\frac\sigma{\sqrt n}`. So if the desired standard error is
`s`, then


`s=\frac\sigma{\sqrt n}\implies \sqrt n=\frac\sigma s\imlies n=(\sigma^2)/(s^2)`