The purpose of the GREEN ACRES REAL ESTATE SYSTEM is to assist agents as they sell houses. Sellers contact the agency, and an agent is assigned to help the seller complete a LISTING REQEUEST. Information about the house and lot taken from that request is stored in a file. Personal information about the sellers is copied by the agent into a sellers file.

When a buyer contacts the agency, he or she fills out a BUYER REQUEST. Every two weeks, the agency sends prospective buyers AREA REAL ESTATE LISTINGS and an ADDRESS CROSS REFERENCE LISTING containing actual street addresses. Periodically, the agent will find a particular house that satisfies most or all of a specific buyer's requirements, as indicated in the BUYER'S REQUISREMENTS STATEMENT distributed weekly to all agents. The agent will occasionally photocopy a picture of the house along with vital data and send the MULTIPLE LISTING STATEMENT (MLS) to the potential buyer.

When the buyer selects a house, he or she fills out a OFFER that is forwarded through the real estate agency to the seller, who responds with either an OFFER ACCEPTANCE or a COUNTEROFFER. After an offer is accepted, a PURCHASE AGREEMENT is signed by all parties. After a PURCHASE AGREEMENT is notarized, the agency sends an APPRAISAL REQUEST to an appraiser, who appraises the value of the house and lot. The agency also notifies its finance company with a FINANCING APPLICATION. 

Based on the above case study

a) Draw the following diagram:
[20 marks]
1. Context level Data Flow Diagram 
2. A Functional Decomposition Diagram
3. An Event Response List and Event Diagram for each events you identify 

b) Now draw a Data to Process CRUD Matrix to check the consistency of your models.