Cinema B $(20$ points$)$

The last several years have witnessed decreased demand for movie theatres due to the COVID$-19$

pandemic and a rise in movies becoming available to customers over streaming services. To account

for decreased demand, a movie theatre named Cinema B modified its business strategy with an aim to

attracting high$-$paying couples looking for a premium date$-$night experience. The changes to its

business strategy have included $(1)$ replacing traditional chairs in auditoriums with reclining two$-$

person sofas, $(2)$ allowing couples to order high$-$quality entr$$es that are delivered directly to their

seats during the movie, and $(3)$ hiring employees to welcome arriving couples and walk them to their

auditoriums and seats. With these changes, Cinema B now processes each couple through four

activities that are conducted in the sequence described below. $($The time required for each activity is

shown in parenthesis$)$:

Activity $1$: Welcome couple when they enter the cinema and scan their tickets. $(5$ minutes$)$

Activity $2$: Lead the couple to the auditorium and seats specified on their ticket $(15$ minutes$)$

Activity $3$: Take the couple$$s dinner order. $(10$ minutes$)$

Activity $4$: Deliver the entr$$es to the couple $(10$ minutes$)$

Three workers $($W$1,$ W$2,$ W$3)$ are assigned to the five activities in the following way: