P$($component works$)+[$P$($component does not work$)$ x P$($switch works $)$ P$($ backup component works $)]$ The Covid$-19$ testing center has a computer which has three modules necessary to work so they can test samples. In order for the computer to function properly, all three modules must function. Two of the modules have reliability's of $\mathrm{.}97,$ and the other has a reliability of $\mathrm{.}99.$ If the backup computer must be activated by a switch