Applied Math - Fractions - Cups in a Recipe

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Introduction

The box of pancake mix tells us how much of each ingredient we should mix in order to cook a batch of pancakes. It’s often easy to cut that recipe in half! We just have to divide each quantity by two. Half a cup of vegetable oil becomes a fourth of a cup.

What if we want three-fourths of a recipe?

What do we do if the recipe calls for \(\frac{2}{3}\)ths of a cup of flour, but we have already added \(\frac{1}{2}\) of a cup? What if we cannot start over because we have limited ingredients and the flour is now mixed with the egg?

Example:

1.

A father is in charge of the Saturday morning breakfasts in the home. They always make waffles. They tried making the full recipe that is suggested on the side of the box but it turned out that it created a few too many pancakes. They tried making half the recipe but it ended up being too little. They want to make \(\frac{3}{4}\)ths of the recipe.

If the recipe calls for \(2\) cups of flower, how many cups should they measure out for \(\frac{3}{4}\)ths of the recipe?

To calculate \(\frac{3}{4}\)ths of a quantity, multiply the quantity by \(\frac{3}{4}\)ths.

\[2 \text{ cups} \cdot \frac{3}{4} =\]

\[\frac{2}{1} \text{ cups} \cdot \frac{3}{4} =\]

\[\frac{6}{4} =\]

\[\frac{3}{2} =\]

\[1 \frac{1}{2}\] cups.

Practice Problems

1. If the recipe calls for \(1\) and \(\frac{3}{4}\) cups of sugar, how many cups should they measure out for \(\frac{1}{2}\) of the recipe?



2. If the recipe calls for \(1\) and \(\frac{3}{4}\) cups of sugar, how many cups should they measure out for \(\frac{3}{4}\)ths of the recipe?