To find the average commission rate on a total sales amount, we can break down the sales into the appropriate ranges and apply the corresponding commission percentages. Let's assume the total sales for the month are $S$. Here is how we approach the problem:

Given commission structure:

1. 2.4% on the first $100,000 in sales.
2. 3.2% on the next $200,000.
3. 4.7% on sales beyond $300,000.

Let’s calculate the total commission and average commission rate step-by-step based on different total sales amounts. Please provide the total sales amount for a specific month, or if you'd like, I can work out a general example first.

Do you want me to continue with an example, or would you prefer to provide a specific sales amount for calculation?