Answer:
a.) Number of 3/4 cup servings in 5 1/2 cups = 5 1/2 / 3/4 = 11/2 / 3/4 = 11/2 x 4/3 = 44/6 = 7 1/3
Therefore, Zoey did not make enough 3/4 cup servings for everyone.
b.) For everyone to have a serving, we have 5 1/2 cups which we want to go round ten people, so each person should get 5 1/2 / 10 = 11/2 / 10 = 11/2 x 1/10 = 11/20.
So the serving should be 11/20 cup for everyone to get serving.
c.) If she uses the 3/4 cup serving, then she will need 3/4 x 10 = 30/4 = 7 1/2 cups altogether.
Therefore, she will need to make extra 7 1/2 - 5 1/2 = 2 cups of trail mix.