To find the unit rate price per ounce of the 64 oz bottle that costs $3.20, you can divide the total price by the total number of ounces:
\[ \text{Unit price per ounce} = \frac{\text{Total price}}{\text{Total ounces}} = \frac{3.20}{64} \]
Calculating that:
\[ \text{Unit price per ounce} = \frac{3.20}{64} = 0.05 \]
So the unit rate price per ounce is $0.05.