Initial design of a system yields three sub systems with reliabilities: $0\mathrm{.}7,0\mathrm{.}6,$ and

$.$ The overall reliability goal is $0\mathrm{.}9.$ Suppose the overall budget is $10$ components. What

should be the minimal value of $$ that will allow you to reach the reliability goal? If you are

given three more modules what is the maximum reliability you can reach from the design

you obtained for the above problem?