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$).$

a$)$ Welding is the bottleneck.

b$)$ The bottleneck time is $30$ minutes per unit $($round your response to two decimal places$).$

c$)$ The throughput time of the overall system is $37\mathrm{.}5$ minutes $($round your response to two decimal places$).$