Considering a system with its Reliability Block Diagram $($RBD$)$ illustrated below and assuming every component works independently. The reliabilities of components $1$ and $5$ are given as $R_1=R_5=0\mathrm{.}9,$ the reliabilities of components $2,3,$ and $4$ are given as $R_2=R_3=R_3=0\mathrm{.}8,$ and the reliabilities of components $6,7,$ and $8$ are given as $R_6=R_7=R_8=0\mathrm{.}7.$ As shown in