Final answer:
To find the amount of flour needed for four eggs in a recipe that calls for one egg for every three cups of flour, use proportions to determine that you need 12 cups of flour.
Step-by-step explanation:
If a pancake recipe calls for one egg for every three cups of flour, and you have four eggs, you can calculate the required amount of flour by setting up a proportion based on the recipe's egg-to-flour ratio:
1 egg : 3 cups flour = 4 eggs : x cups flour
To solve for x, you multiply both sides of the equation by x and then divide by the number of eggs (which is 1 in the recipe's ratio) to isolate x:
4 eggs × 3 cups flour = 1 egg × x cups flour
12 cups flour = x cups flour
Therefore, for four eggs, you need 12 cups of flour. This is a basic example of using proportions to scale a recipe, which is a common application of ratios in mathematics.