$2$ ?tats

A system is composed of four parts, J$,$ ?K$,$ ?L$,$ ?and M$.$ ?All four must function for the system to function. The four component reliabilities are $0\mathrm{.}99,0\mathrm{.}98,0\mathrm{.}992,$ ?and $0\mathrm{.}998.$ ?The desienters at: considering putting an $80\%$ ?reliable backup at $K.$ ?This backup will change the system feliability from to

$21$

$0\mathrm{.}9762$;$0\mathrm{.}9605$

$0\mathrm{.}9605$;$0\mathrm{.}9762$

$0\mathrm{.}9605$ ?; some smaller value

$0\mathrm{.}9605$;$0\mathrm{.}996$

$0\mathrm{.}98$;$0\mathrm{.}99$