Answer:
a) The bottleneck of the process is work station B
b) 1,43 Units per hour
Step-by-step explanation:
a) The bottleneck of a process is the activity in a process chain that limits the capacity of the whole process. 
In this case we have two parts 
- PART 1 : each part is processed in workstation A for 12 min and then for 20 minutes in workstation B, so it takes 32 minutes until it arrives to workstation D where it will be assebly with part 2 
- PART 2: each part is processed in workstation C for 15 minutes until it reachs workstation D for the final assembly 
- But, as we can see, part two will be waiting for (32-15= 17) 17 minutes until PART 1 arrives. 
As we can see, the workstation B is the bottleneck of the process because it limits the capacity of the whole chain. 
b) lets calculate the how long it takes to produce 1 unit: 
We have already calculated that it takes 32 minutes to have the two parts in workstation D. After thata they will be assembles fpr 10 more minutes, so it takes 32+10= 42 minutes to produce one unit. 
Now, let's see how many pieces we can produce in an hour: (60 min/ hour)/42(min/unit) = 1,43 units /hour