9.47 Consider the following 3NF relations about a sorority or fraternity:

MEMBER(Member_ID,Name,Address,Dues_Owed)

OFFICE(Office_Name,Officer_ID,Term_Start_Date,Budget)

EXPENSE(Ledger_Number,Office_Name,Expense_Date,Amt_Owed)

PAYMENT(Check_Number,Expense_Ledger_Number,Amt_Paid)

RECEIPT(Member_ID,Receipt_Date,Dues_Received)

COMMITTEE(Committee_ID,Officer_in_Charge)

WORKERS(Committee_ID,Member_ID)

a. Foreign keys are not indicated in these relations. Decide which attributes are foreign keys and justify your decisions.

b. Draw an E-R diagram for these relations, using your answer to Problem and Exercise 9-47a.

c. Explain the assumptions you made about cardinalities in your answer to Problem and Exercise 9-47b. Explain why it is said that the E-R data model is more expressive or more semantically rich than the relational data model.