Problem 1: Create a pandas Series representing the prices of three items (Apple: 1.50, Banana: 0.75, Orange: 1.25) using a dictionary. Then, apply a 10% discount to all items at once.

Problem 2: Create a DataFrame from a dictionary containing ‘Name’, ‘Age’, and ‘City’ for four people. Filter the DataFrame to display only the rows where the person is 30 years old or older.

*Problem 3: Create a DataFrame containing a list of employees with their ‘Department’ (e.g., Sales, IT) and ‘Salary’. Calculate the average (mean) salary for each department.