Add a calculated column and a total

The steps

The exact sequence, in order.

1. 01

   Type df["amount"] = df["quantity"] * df["unit_price"].

2. 02

   Type print(df["amount"].sum()): 14976.0.

3. 03

   Type print(df["amount"].mean()): 48.0, the average basket.

4. 04

   Note these two numbers: you’ll use them to check.