$1\mathrm{.}10$ For the system shown in Figure $1\mathrm{.}23,$ the following CBs are known to operate: $($a$)$ B$1$and B$2$; $($b$)$ B$3,$ B$4,$ B$1,$ B$5,$ and B$7$; $($c$)$ B$7$ and B$8$; $($d$)$ B$1,$ B$3,$ B$5,$ and B$7.$ Assuming that all primary protection has worked correctly, where is the fault located in eachof these cases?$($Assume dead tank breakers, throw in some zones of protection$)$