I need the excel file using Solver for the solution question b and c$,$ and also the explanation on how to do it

$^(1)$ This case is based on an actual project completed by a team of master's students in the Department of Engineering$-$Economic Systems and Operations

Research at Stanford University. $($Following a later merger, this department now is the Department of Management Science and Engineering.$)$

After the consultants submitted these forecasts, Lenny be$-$

came interested in the percentage of calls from Spanish

speakers since the hospital services many Spanish patients.

Lenny knows that he has to hire some operators who speak

Spanish to handle these calls. The consultants performed fur$-$

ther data collection and determined that on average, $20$ per$-$

cent of the calls were from Spanish speakers.

Given these call forecasts, Lenny must now decide how

to staff the call center during each $2$ hour shift of a weekday.

During the forecasting project, Creative Chaos Consultants

closely observed the operators working at the individual clin$-$

ics and departments and determined the number of calls op$-$

erators process per hour. The consultants informed Lenny that

an operator is able to process an average of six calls per hour.

Lenny also knows that he has both full$-$time and part$-$time

workers available to staff the call center. A full$-$time employee

works $8$ hours per day, but because of paperwork that must

also be completed, the employee spends only $4$ hours per day

on the phone. To balance the schedule, the employee alter$-$

nates the $2-$hour shifts between answering phones and com$-$

pleting paperwork. Full$-$time employees can start their day ei$-$

ther by answering phones or by completing paperwork on the

first shift. The full$-$time employees speak either Spanish or

English, but none of them are bilingual. Both Spanish$-$speak$-$

ing and English$-$speaking employees are paid $$10$ per hour

for work before $5$ P$.$M$.$ and $$12$ per hour for work after $5$ P$.$M$.$

The full$-$time employees can begin work at the beginning of

the $7$ A$.$M$.$ to $9$ A$.$M$.$ shift, $9$ A$.$M$.$ to $11$ A$.$M$.$ shift, $11$ A$.$M$.$ to

$1$ P$.$M$.$ shift, or $1$ P$.$M$.$ to $3$ P$.$M$.$ shift. The part$-$time employees

work for $4$ hours, only answer calls, and only speak English.

They can start work at the beginning of the $3$ P$.$M$.$ to $5$ P$.$M$.$

shift or the $5$ P$.$M$.$ to $7$ P$.$M$.$ shift, and like the full$-$time em$-$

ployees, they are paid $$10$ per hour for work before $5$ P$.$M$.$

and $$12$ per hour for work after $5$ P$.$M$.$

For the following analysis consider only the labor cost

for the time employees spend answering phones. The cost

for paperwork time is charged to other cost centers.

$($a$)$ How many Spanish$-$speaking operators and how many English$-$

speaking operators does the hospital need to staff the call cen$-$

ter during each $2-$hour shift of the day in order to answer all

calls? Please provide an integer number since half a human op$-$

erator makes no sense.

$($b$)$ Lenny needs to determine how many full$-$time employees who

speak Spanish, full$-$time employees who speak English, and part$-$

time employees he should hire to begin on each shift. Creative

Chaos Consultants advise him that linear programming can be

used to do this in such a way as to minimize operating costs

while answering all calls. Formulate a linear programming

model of this problem.

$($c$)$ Obtain an optimal solution for the linear programming model

formulated in part $($b$)$ to guide Lenny's decision.

$($d$)$ Because many full$-$time workers do not want to work late into the

evening, Lenny can find only one qualified English$-$speaking op$-$

erator willing to begin work at $1$ P$.$M$.$ Given this new constraint,

how many full$-$time English$-$speaking operators, full$-$time Spanish$-$

speaking operators, and part$-$time operators should Lenny hire for

each shift to minimize operating costs while answering all calls?

$($e$)$ Lenny now has decided to investigate the option of hiring bilin$-$

gual operators instead of monolingual operators. If all the op$-$

erators are bilingual, how many operators should be working

during each $2-$hour shift to answer all phone calls? As in part

$($a$),$ please provide an integer answer.

$($f$)$ If all employees are bilingual, how many full$-$time and part$-$time

employees should Lenny hire to begin on each shift to minimize

operating costs while answering all calls? As in part $($b$),$ for$-$

mulate a linear programming model to guide Lenny's decision.

$($g$)$ What is the maximum percentage increase in the hourly wage

rate that Lenny can pay bilingual employees over monolingual

employees without increasing the total operating costs?

$($h$)$ What other features of the call center should Lenny explore to

improve service or minimize operating costs?