To find the unit rate of chocolate powder per cup of milk in Mixture X, we start with the original ratio of chocolate powder to milk:
- Chocolate Powder: 4 tablespoons
- Milk: 3 cups
We need to find how much chocolate powder is used for 1 cup of milk. To do this, we can divide the amount of chocolate powder by the amount of milk. Since we are looking for the rate per 1 cup, we can set up the following calculation:
\[ \frac{4 \text{ tablespoons}}{3 \text{ cups}} = \frac{4}{3} \text{ tablespoons per cup} \]
Now, we multiply by the factor of \(\frac{3}{1}\) to convert it into a unit rate:
\[ \frac{4 \text{ tablespoons}}{3 \text{ cups}} \times \frac{3}{1} = \frac{4 \times 3}{3} = \frac{4}{1} \]
Thus, the unit rate is:
\[ \frac{4}{3} \text{ tablespoons of chocolate powder per cup of milk} \]
This is the final answer in fraction form.