Question

a cookie recipe states for every 3 cups of flour, 1 1/2 teaspoons of vanilla are needed. how many teaspoons are needed for 5 cups of flour?

Explanation:

Step1: Find the ratio of vanilla to flour

The ratio of vanilla (in teaspoons) to flour (in cups) is $1\frac{1}{2}:3$. Convert $1\frac{1}{2}$ to an improper fraction, which is $\frac{3}{2}$. So the ratio is $\frac{3}{2}:3$, or simplifying, divide both parts by 3: $\frac{1}{2}:1$, meaning for 1 cup of flour, we need $\frac{1}{2}$ teaspoon of vanilla.

Step2: Calculate vanilla for 5 cups of flour

If for 1 cup of flour we need $\frac{1}{2}$ teaspoon of vanilla, then for 5 cups, we multiply the amount per cup by 5. So the amount of vanilla is $5\times\frac{1}{2}=\frac{5}{2} = 2\frac{1}{2}$ teaspoons.

Answer:

$2\frac{1}{2}$ teaspoons (or $\frac{5}{2}$ teaspoons)