​Bill's Barbershop has two barbers available to cut​ customer's hair. Both barbers provide roughly the same experience and​ skill, but one is just a little bit slower than the other. The process flow below shows that all customers go through steps B1 and B2 and then can be served at either of the two barbers at step B3. The process ends for all customers at step B4. The numbers in parentheses indicate the minutes it takes that activity to process a customer.
A. How long does it take the average customer to complete this process.
B. What single activity is the bottleneck for the entire process?