$13\mathrm{.}13$ Back to the Server Farm

Consider again the server farm from Exercise $13\mathrm{.}2.$ Use what you learned in

Exercise $13\mathrm{.}11$ to derive expressions for

$($a$)$ the tail behavior of response time, $P\{T>t\}$

$($b$)$ variance of response time, Var$(T).$