Example $64.$

Consider a system having $10$ subsystems whose reliability si desired to be $0\mathrm{.}70.$ The estimated reliabilities of the first five subsystems are $0\mathrm{.}95,0\mathrm{.}90,0\mathrm{.}94,0\mathrm{.}96,$ and $0\mathrm{.}98$ respectively. The reliabilities of the first two of these cannot be improved while the remaining three are available for possible improvement. The estimated reliabilities of the last five subsystems are not known but the following data are known about these:

$1.$ Subsystems $7$ and $8$ operate for $75\%$ and $50\%$ of the mission time respectively. All other subsystems operate for complete mission time. $2.$ Redundancy can be used at subsystems $6$ and $10$ only.

$3.$ Maintenance is not possible for any of the subsystems.

$4.$ The values of complexity factor, cost factor and state of art factor for these subsystems are: