Fraction stories

Question

Susie wants to make some hot cereal for breakfast. The directions say to use 3 cups of water with 1 cup of cereal for 4 servings. Susie only eants 1 serving. How much cereal should she use? How much water should she use?

Answer 1

You set up this type of problem as a ratio. 3/4 = x/1

Meaning: 3 cups of cereal over 4 servings equals x cups of cereal over 1 serving.

Then you cross multiply: 3 x 1 = 3 4 x x = 4x

Now you have 4x = 3

Then you divide both sides by 4: x = 3/4

You need 3/4 cup of cereal.

Do the same thing for the water: 1/4 = x/1

1 = 4x

x = 1/4; You need 1/4 cup of water