Here is a Python solution for your problem:

```python
class BankAccount:
def __init__(self, account_number, account_holder_name, balance):
self.account_number = account_number
self.account_holder_name = account_holder_name
self.balance = balance

def display(self):
print(f"Account Number: {self.account_number}")
print(f"Account Holder: {self.account_holder_name}")
print(f"Balance: {self.balance}")

class SavingsAccount(BankAccount):
def __init__(self, account_number, account_holder_name, balance, interest_rate):
super().__init__(account_number, account_holder_name, balance)
self.interest_rate = interest_rate

def add_interest(self):
self.balance += (self.balance * self.interest_rate) / 100

def display(self):
super().display()
print(f"Interest Rate: {self.interest_rate}%")

# Test Case 1
print("Test Case 1:")
account1 = SavingsAccount(784569874, "Ravi", 50000, 2)
account1.display()
account1.add_interest()
print("After adding interest:")
account1.display()

# Test Case 2
print("
Test Case 2:")
account2 = SavingsAccount(547981235, "Ramana", 90000, 2.5)
account2.display()
account2.add_interest()
print("After adding interest:")
account2.display()
```

This code first defines a `BankAccount` class with an `__init__` method to initialize the account number, account holder name, and balance, and a `display` method to print these details.

Then it defines a `SavingsAccount` class that inherits from `BankAccount` and adds an interest rate attribute and an `add_interest` method that increases the balance by the appropriate amount of interest. The `display` method in `SavingsAccount` calls the `display` method in `BankAccount` (using `super().display()`) and then prints the interest rate.

The test cases create instances of `SavingsAccount`, display their details, add interest, and then display the updated details.

Question

Here is a Python solution for your problem:

```python
class BankAccount:
    def __init__(self, account_number, account_holder_name, balance):
        self.account_number = account_number
        self.account_holder_name = account_holder_name
        self.balance = balance

def display(self):
        print(f"Account Number: {self.account_number}")
        print(f"Account Holder: {self.account_holder_name}")
        print(f"Balance: {self.balance}")

class SavingsAccount(BankAccount):
    def __init__(self, account_number, account_holder_name, balance, interest_rate):
        super().__init__(account_number, account_holder_name, balance)
        self.interest_rate = interest_rate

def add_interest(self):
        self.balance += (self.balance * self.interest_rate) / 100

def display(self):
        super().display()
        print(f"Interest Rate: {self.interest_rate}%")

# Test Case 1
print("Test Case 1:")
account1 = SavingsAccount(784569874, "Ravi", 50000, 2)
account1.display()
account1.add_interest()
print("After adding interest:")
account1.display()

# Test Case 2
print("
Test Case 2:")
account2 = SavingsAccount(547981235, "Ramana", 90000, 2.5)
account2.display()
account2.add_interest()
print("After adding interest:")
account2.display()
```

This code first defines a `BankAccount` class with an `__init__` method to initialize the account number, account holder name, and balance, and a `display` method to print these details.

Then it defines a `SavingsAccount` class that inherits from `BankAccount` and adds an interest rate attribute and an `add_interest` method that increases the balance by the appropriate amount of interest. The `display` method in `SavingsAccount` calls the `display` method in `BankAccount` (using `super().display()`) and then prints the interest rate.

The test cases create instances of `SavingsAccount`, display their details, add interest, and then display the updated details.

Knowee AI · Accepted Answer