A prodact is made of components $A,B,C,$ and $D.$ The chance of failure of the four components are as follows $0\mathrm{.}01,0\mathrm{.}06,0\mathrm{.}04,$ and $0\mathrm{.}08$ respectively.

What is the overall reliability of this product, assume series combination?

b$.$ The decision maker is considering either arrangement $1($Fig$.1),$ or arrangement $2($Fig$.2)$ in order to enhance the reliability of the product, which arrangement has to be selected that has the highest reliability.

c$.$ What is the overall reliability improvement of the selected one $($in part b$)$ over the arrangement in nart a

Figwre $2$: Arrangewent $2$