Consider the following batch-flow process consisting of three process steps performed by three machines:
Step 1→→→→Δ→→→→ Step 2 →→→Δ→→→→ Step 3
Activity Time: Activity Time: Activity Time:
0.25 Minute/Part 0.20 Minute/Part 0.15 Minute/Part
Setup Time: Setup Time: Setup Time:
30 Minutes 20 Minutes 45 Minutes

Work is processed in batches at each step. Before a batch is processed at a step, the machine at that step must be set up. (During a setup, the machine is unable to process any product.) Assume that there is a dedicated setup operator for each machine (i.e., there is always someone available to perform a setup at each machine.)
(A) For what batch sizes is step 1 the bottleneck?