1. **State the problem:** We want to find how much sugar is needed to make 10 dozen cookies if 2 dozen cookies require 1 \frac{1}{3} cups of sugar. 2. **Convert mixed number to improper fraction:** 1 \frac{1}{3} = \frac{4}{3} cups of sugar. 3. **Set up the proportion:** Sugar needed is proportional to the number of cookies. So, sugar for 10 dozen = \frac{10}{2} \times \frac{4}{3}. 4. **Calculate:** \frac{10}{2} = 5 5 \times \frac{4}{3} = \frac{20}{3} = 6 \frac{2}{3} cups. 5. **Final answer:** You need $6 \frac{2}{3}$ cups of sugar to make 10 dozen cookies.