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

def add_interest(self):
self.balance += (self.balance * self.interest_rate) / 100
print(f"After adding interest: Balance: {self.balance}")

# Test Case 1
account1 = SavingsAccount(784569874, "Ravi", 50000, 2)
account1.display()
account1.add_interest()

# Test Case 2
account2 = SavingsAccount(547981235, "Ramana", 90000, 2.5)
account2.display()
account2.add_interest()
```

This code first defines a `BankAccount` class with attributes for account number, account holder name, and balance. It also has a `display` method to print these details.

Then it defines a `SavingsAccount` class that inherits from `BankAccount`. It adds an additional attribute for interest rate and a method `add_interest` to increase the balance by the appropriate amount of interest.

The test cases create instances of `SavingsAccount`, display their details, and add interest to their balance.

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

def add_interest(self):
        self.balance += (self.balance * self.interest_rate) / 100
        print(f"After adding interest: Balance: {self.balance}")

# Test Case 1
account1 = SavingsAccount(784569874, "Ravi", 50000, 2)
account1.display()
account1.add_interest()

# Test Case 2
account2 = SavingsAccount(547981235, "Ramana", 90000, 2.5)
account2.display()
account2.add_interest()
```

This code first defines a `BankAccount` class with attributes for account number, account holder name, and balance. It also has a `display` method to print these details.

Then it defines a `SavingsAccount` class that inherits from `BankAccount`. It adds an additional attribute for interest rate and a method `add_interest` to increase the balance by the appropriate amount of interest.

The test cases create instances of `SavingsAccount`, display their details, and add interest to their balance.

Knowee AI · Accepted Answer