The three$-$station work cell illustrated in the figure below has a product that must go through one of the two machines at station $1($they are parallel$)$ before proceeding to station $2.$

a$)$ The bottleneck time of the system is $10$ minutes per unit $($enter your response as a whole number$).$

b$)$ Station $3$ is the bottleneck station.

c$)$ The throughput time is $18$ minutes $($enter your response as a whole number$).$

d$)$ If the firm operates $9$ hours per day, $5$ days per week, the weekly capacity of this work cell is units $($enter your response as a whole number$).$N