A production process at Brianna Bryant Manufacturing is shown in the figure below. The drilling operation occurs separately$$ from, and simultaneously$$ with, the sawing and$$ sanding, which are independent sequential operations. A product needs to go through only one of the three assembly operations$($the operations are in$$ parallel$).$

Sanding

Drilling

Welding

Assembly

$5$ units$/$hr

$6$ units$/$hr

$2\mathrm{.}2$ units$/$hr

$0\mathrm{.}7$ units$/$hr

Assembly

Assembly

$0\mathrm{.}7$ units$/$hr

$0\mathrm{.}7$ units$/$hr

$1\mathrm{.}8$ units$/$hr

Sawing