Educational Associates is upgrading its computing power. It will be installing

Educational Associates is upgrading its computing power. It will be installing new computers in the next 4 months across several departments of the company.
The plan is to install in a staggered basis according to the schedule below. The numbers of users in the departments that have to be supported are indicated
below:

Month

Department

Number of users to be supported

1

Assessment

50

2

Marketing

60

3

Admin

70

4

Others

30

The company is considering four types of computers to serve their needs. The following table shows the various computers the number of users that can be
supported by a computer and the unit purchase costs.

Computer type

Number of users that can be supported

Unit Purchase Cost

Standard PC

Up to 20

$ 3000

Enhanced PC

Up to 40

$ 5000

Small Workstation

Up to 100

$ 12000

Large Workstation

Up to 1000

$ 30000

a. The company wants to determine the number and type of computers to purchase on a month-to-month basis. To
do this formulate in Excel for each month the linear program to determine the number and type of computer to purchase in order to minimize the cost in that
month that will support the required number of new users given the results in the preceding month. How many and which type of computers should be bought
in each month? What is the total cost for all 4 months under this plan?

b. Is it possible to purchase a larger computer in the initial months in order to support users in the final
months? The company decides to evaluate the number and type of computers to purchase over the entire planning period rather than month-to-month basis.
To do this you need to formulate in Excel the linear program to determine the number and types of computers to purchase in which months to minimize the total
cost and support all new users. How many and what type of computers should be purchased in each month? What is the total cost of this plan?

c. Why is there a difference between these two plans? Comment on this result.

[Hint: The decision variables should be constrained to be integers].