Given the data below, what is the lower control limit for the $x-$bar chart?

$\backslash$table$[[,$Time $1,$Time $2,$Time $3,$Time $4],[$Observation $1,5\mathrm{.}15,5\mathrm{.}00,4\mathrm{.}90,4\mathrm{.}85],[,,,,],[$Observation $2,5\mathrm{.}05,4\mathrm{.}90,4\mathrm{.}75,5\mathrm{.}15],[$Observation $3,4\mathrm{.}95,4\mathrm{.}90,5\mathrm{.}10,5\mathrm{.}25],[$Observation $4,4\mathrm{.}80,5\mathrm{.}05,5\mathrm{.}15,5\mathrm{.}20],[$Observation $5,5\mathrm{.}00,5\mathrm{.}20,4\mathrm{.}85,5\mathrm{.}05],[4\mathrm{.}75,,,,],[5\mathrm{.}00,,,,],[5\mathrm{.}79,,,,],[$none of the above,,,,$],[4\mathrm{.}80,,,,]]$