EE/GG 550

Lab 4

Description:

You are hired as a business consultant for the world famous cheese store "The Mouse Trap".  The objective of this model is to set up a model that will enable you to estimate average shopping time - which is defined as the average time that has passed since customers enter the store until they leave the store. The ultimate objective is then to minimize average shopping time.

The store has one service center and one cash register, and only two employees one working at the service center and one operating the cash register. The customers immediately after entering the store wait in line to get their favorite cheese sliced at the service center. After receiving the sliced cheese, each customer browses for a few minutes and then goes directly to the checkout line at the cash register, and leaves the store immediately after paying. 

Assumptions:

1.     There is one entrance to the store, one service center and one cash register.

2.     Initial conditions:

a.     One customer at the service center, no one is waiting in line.

b.     4 customers already browsing.

c.     10 customers already in the checkout line.

3.     Every 4 minutes one more customer arrives.

4.     It takes 5 minutes to get service at the service center - same time for everyone.

5.     Only one person at a time gets service.

6.     Everyone browses for 5 minutes, then proceeds to the checkout line.

7.     Only one person at a time at the cash registrar.

8.     Takes 2 minutes to pay - same time for everyone.

Task:

1. Run the model for 2 hours.

2. Plot the service queue and the checkout queue, explain the dynamics you observe.

3. Given the conditions above estimate the average shopping time for the store, and the average shopping time per each customer currently leaving the store. Explain the trends you observe in both variables.

4. Assume that you hire a third employee that can either work at the service center (cutting service time in half) or operate a second cash register.  This third employee is supposed to go back and forth between the service station and the cash register, but cannot be at two places at the same time. Create a model that captures when you would like that third person to be at each station, with the objective in mind to minimize average shopping time.  Be careful to explicitly state any new assumptions you make.