$7.$ A system consists of four subassemblies connected in series. The individual subassembly reliabilities are as follows:

Subassembly A $=0\mathrm{.}98$

Subassembly B $=0\mathrm{.}85$

Subassembly C $=0\mathrm{.}90$

Subassembly D $=0\mathrm{.}88$

Determine the overall system reliability.

$8.$ A system consists of three subsystems in parallel $($assume operating redundancy$).$ The individual subsystem reliabilities are as follows:

Subsystem A $=0\mathrm{.}98$

Subsystem B $=0\mathrm{.}85$

Subsystem C $=0\mathrm{.}88$

Determine the overall system reliability.