Consider the following simple two$-$step process: flow units go through Steps A and B in sequence. Step A has a processing time of $1$ minute per unit, but no setup is required. Step B has a processing time of $0\mathrm{.}1$ minutes per unit, but a setup time of $19\mathrm{.}61$ minutes is required per batch. A buffer with ample inventory is allowed between the two steps.

$2.$ What is the batch size $($as an integer$)$ that maximizes the flow rate of this process with minimal inventory? Assume there is ample demand.