Natalia, a new MBA graduate, recently took a position with OU $3$D Prosthetics, a small healthcare manufacturer which specializes in making prosthetic hands. Their products provide individuals who have lost a hand due to injury, development issues, or other diseases, the ability to pick$-$up objects and function in everyday activities.

Given the current scale of their operations, OU $3$D Prosthetics uses $3$D printing to produce prototypes, which they then sell to hospitals and healthcare providers around the country. These prototypes are fully functioning models that demonstrate the abilities of the final product, which allow patients, along with their doctors, to determine whether they want to pursue a prosthetic hand from OU $3$D Prosthetics. OU $3$D Prosthetics provides two different versions of prototypes, which differ in their level of detail: Model B is a basic model, and Model X is a higher$-$end version with greater durability and a more accurate representation of the final product.

The basic process for producing the two prototypes consists of the same three steps: setup, printing, and assembly. During setup, an operator prepares the thermoplastic material polylactide material for a single unit. In the printing step, the machines conduct the $3$D printing of the prototypes, which includes the main hand, along with components for fingers, joints, and other details $($this printing step can be done in parallel with the setup step$).$ Lastly, two separate assembly departments handle the process of assembling the components of the two prototypes.

Table $1$ shows the amount of time needed for each prototype. For example, one model B requires $0\mathrm{.}25$ hours for printing $($which accounts for the number of printers and operators, etc$).$ The operators can work for $800$ hours each month for setups. Similarly, the $3$D printers can print for $800$ hours each month. The model B assembly department has a monthly capacity of $1900$ units. The model X assembly department has a monthly capacity of $1400$ units. Currently, OU $3$D Prosthetics is producing and selling $400$ units of model B and $1400$ units of model X per month.