Problem $2.$ A plant manager needs a design for an assembly line to assembly a new product that is being introduced. The time requirements and immediate predecessors for the work elements are as follows:

$\backslash$table$[[\backslash$table$[[$Work$],[$Element$]],$Time $($sec$),\backslash$table$[[$Immediate$],[$Predecessor$]]],[$A$,12,-],[$B$,60,$A$],[$C$,36,-],[$D$,24,-],[$E$,38,$C$,$ D$],[$F$,72,$B$,$ E$],[$G$,14,-],[$H$,72,-],[$I$,35,$G$,$ H$],[$J$,60,$I$],[$K$,12,$F$,$ J$],[$Total $=,435,]]$

If the desired output rate is $30$ units per hour, arrange the activities to $4$ work stations.