Use the table below to answer questions $11$ through $13.$ Demand for a certain subassembly in an engine manufacturing facility in Norfolk, Virginia is $68$ items per eight$-$hour shift or workers. The following $6$ tasks are required to produce one subassembly. Task Time required $($min$)$ Predecessor tasks a $7-$ b $6$ a c $4$ b d $3$ b e $6$ b$,$c f $8$ d$,$e Theoretically, how many stations will be required?