You are required to produce an Entity Relationship Model (diagram) for a very simple electrical utility company prior to a full implementation of a relational database for the company’s activities. Your model should capture the key relationships (mappings) that exist between a small number of Entity Sets. These are provided for you below. In your completed Entity Relationship Model, you should define the Relationship Sets that describe the relationships that exist between the Entity Sets. 
Entity Sets 
Customers
Call Centres
Repair Departments
Installation Departments
Account Departments
Equipment Departments

Relationships (Mappings) 
Many Customers call many Call Centres
Many Call Centres inform a single Repair Department
Many Call Centres inform a single Installation Department
Many Call Centres inform a single Account Department
A single Repair Department visits many Customers
A single Installation Department visits many Customers
A single Account Department deals with many Customers
Many Equipment Departments deal with many Repair Departments