To find the unit rate price per ounce for the hot chocolate, you can divide the total cost by the total number of ounces.
The cost of the hot chocolate is $5.00, and the volume is 20 ounces.
\[ \text{Unit rate price per ounce} = \frac{\text{Total Cost}}{\text{Total Ounces}} = \frac{5.00}{20} \]
Calculating this gives:
\[ \text{Unit rate price per ounce} = \frac{5.00}{20} = 0.25 \]
Thus, the unit rate price per ounce for her hot chocolate is $0.25 per ounce.