A Product requires two sequential machine operations. The first take $3\mathrm{.}5$ minutes and defect is $12.$ The second takes $6\mathrm{.}0$ minutes and defect percentage is $7.$ Assuming $250$ workdays per year and a daily shift of $8$ hours, it is desired to determine the minimum fractional number of machines to manufacture $50,000$ units per year.

In other similar plant belonging ti the same company, part annual data on identical operations and working conditions indicae that $10$ machines were out of production a total number of $2198$ hours due to setup and $2052$ hours due to machine unavailability. Determine number of machines.