deletions | additions       diff --git a/subsection_Question_a_At_rush__.tex b/subsection_Question_a_At_rush__.tex  index a3a01f0..ef09742 100644  --- a/subsection_Question_a_At_rush__.tex  +++ b/subsection_Question_a_At_rush__.tex 
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\subsection{Question a}  At rush hour, the traffic intensity is $a = 4.5$ \textit{Erlangs}\footnote{$3$ groups per minute times $1.5$ minutes service time}. With $c=5$ elevators, the average server utilization of corporate A is very high: $\rho = 4.5 / 5 = 0.9$. The average waiting time \eqref{Tim} is $2'$ $T_w=2'$  $17''$, that is, it is \textbf{ longer} than the average service time ($W_s=1'$ $30''$). The overall time needed on average by the employees to reach their floor $T_w + W_s$ is $3'$ $47''$.\\ By adding one more elevator, so that $c=6$, the management of corporate B decreases the average server utilization to $\rho = 4.5 / 6 = 0.75$. The average waiting time \eqref{Tim} is $25''$, $T_w=25''$,  that is, it is \textbf{one third} of the average service time ($W_s=1'$ $30''$). The overall time needed on average by the employees to reach their floor $T_w + W_s$ is $1'$ $55''$\\ The building manager of corporate B was able to take advantage of the non-linearity of the problem: the increase by $20\%$ in the number of elevators translate into the decrease by $50\%$ of the overall time needed on average by the employees to reach their floor.     
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