Question number $7.$

Suppose a random sample of $50$ measurements is selected from a population with a mean of $55$ and a variance of $400.$ Select the pair that is the mean and standard error of $\stackrel{}{x}.0[55,2\mathrm{.}828]$

$55,2928$

$50,2\mathrm{.}928$

$[55,3\mathrm{.}028]$

$[55,3128]$

None of the above