1. (20 points) Construct an E-R diagram for a university registrar's office. The office maintains data about each class, each instructor and each student. The data maintained about a class includes the instructor, the enrollment, and the time and place of class meetings. For each student-class pair, a grade is recorded. Use your best judgement in choosing appropriate attributes, and be sure to indicate the mapping cardinality of any relationship sets in your diagram.
2. Consider the following E-R diagram for a bank:
   
   

   

   where the date attribute of relationship set Has stores the date on which the customer became the owner of the account.

   1. (5 points) List all candidate keys for entity sets customer and account, and designate a primary key for each. Use your knowledge about these entity sets in determining candidate keys.
   2. (5 points) Using the technique discussed in class, find a superkey for relationship set Has.
   3. (3 points) Find a primary key for relationship set Has.

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