A process that is considered to be in control measures an ingredient in ounces. Below are the last $10$ samples $($each of size n $=5)$ taken. The population process standard deviation is $1\mathrm{.}64.$

Samples Item $1$ Item $2$ Item $3$ Item $4$ Item $5$

$11099813$

$21311121311$

$3139111110$

$4101110911$

$5131191210$

$611117119$

$710101089$

$812109117$

$987111210$

$1011138812$

Standard deviation of the sampling means$=$