$$a$)$ The reliability of the system shown above$=$

$$

$96\mathrm{.}77\%($enter your response as a percentage rounded to two decimal$$ places$).$

Part $3$

$$b$)$ As compared to a system without backup$($shown below$),$

$0\mathrm{.}96$

$0\mathrm{.}96$

$0\mathrm{.}89$

the reliability of the system with backup is higher by

$$

enter your response here$\%($enter your response as a percentage rounded to two decimal$$ places$).$