The quality$-$control plan for a certain production process involves taking samples of size $4.$ The results from the last $31\mathrm{.}00$ samples can be summarized as follows:

$31\mathrm{.}00$i$=1$X$$i$=712\mathrm{.}5$

$31\mathrm{.}00$i$=1$Ri$=143\mathrm{.}7$

$31\mathrm{.}00$i$=1$si$=62\mathrm{.}5$

Using the sample ranges, compute the $3\backslash$sigma control limits for the X$$

chart.

$($Round the final answer to three decimal places.$)$