Final answer:
To make 321 cups of eggnog, one would need approximately 142.7 cups of cream, based on the recipe's proportion of 4 cups of cream for every 9 cups of eggnog.
Step-by-step explanation:
To determine how many cups of cream are needed to make 321 cups of eggnog, we must first establish the ratio given by the recipe for 9 cups of eggnog. According to the recipe, 4 cups of cream are used to make 9 cups of eggnog. To find out how much cream is needed for 321 cups of eggnog, we set up a proportion:
4 cups cream / 9 cups eggnog = x cups cream / 321 cups eggnog
Solving for x, which represents the amount of cream needed:
x = (4 cups cream * 321 cups eggnog) / 9 cups eggnog
x = 1284 cups cream / 9
x ≈ 142.7 cups cream
Therefore, 142.7 cups of cream are needed to make 321 cups of eggnog.