Part $5$: Push$/$Pull Production Systems and Basic factory dynamics $(22$ points$)$

$11-$ A product must visit five stations $A,B,C,D$ and then E with the following details. We desire the throughput to be $0\mathrm{.}95$ percent of the bottleneck rate. Find the WIP level required to achieve this under the assumptions of the best case and practical worst case. $(4$ Points$)$

$\backslash$table$[[$Station$,\backslash$table$[[$Number of identical$],[$machines$]],\backslash$table$[[$Average Processing time $($min per$],[$unit$)]]],[$A$,5,50],[$B$,3,20],[$C$,4,30],[$D$,1,20],[$E$,2,10]]$