Please correct the wrong answer!

Oxbridge University maintains a powerful mainframe computer for research use by

its faculty, Ph$.$D$.$ students, and research associates. During all working hours, an

operator must be available to operate and maintain the computer, as well as to

perform some programming services. Beryl Ingram, the director of the computer

facility, oversees the operation. It is now the beginning of the fall semester and Beryl

is confronted with the problem of assigning different working hours to her

operators. Because all the operators are currently enrolled in the university, they are

available to work only a limited number of hours each day. There are six operators

$($four undergraduate students and two graduate students$).$ They all have different

wage rates because of differences in their experience with computers and in their

programming ability. The following table shows their wage rates, along with the

maximum number of hours that each can work each day.

Each operator is guaranteed a certain minimum number of hours per week that will

maintain an adequate knowledge of the operation. This level is set arbitrarily at $9$

hours per week for the undergraduate students $($K$.$ C$.,$ D$.$ H$.,$ H$.$ B$.,$ and S$.$ C$.)$ and $8$

hours per week for the graduate students $($K$.$ S$.$ and N$.$ K$.).$ The computer facility is to

be open for operation from $8$ AM to $10$ PM Monday through Friday with exactly one

operator on duty during these hours. On Saturdays and Sundays, the computer is to

be operated by other staff. Because of a tight budget, Beryl has to minimize cost.

She wishes to determine the number of hours she should assign to each operator

on each day. Formulate and solve a spreadsheet model for this problem.

Determine the total cost.