Part X requires machining on a milling machine with operations A and B required. Find the minimum number of machines required to produce $2500$ parts per week. Assume the company will be operating $5$ days per week, $18$ hours per day. The following information is known:

Operation

Standard Time

Efficiency

Reliability

Scrap

A

$2$ min

$95\%$

$95\%$

$2\%/$

B

$4$ min

$95\%$

$90\%$

$5\%$