According to the recipe the ratio of sparkling water to grape juice = 1 1/2 : 3/4.
Let us convert 1 1/2 into improper fraction and that is 3/2.
Now, 3/2: 3/4 or 3/2 ÷ 3/4 = 3/2 × 4/3 = 2/1 or 2:1.
Therefore, sparkling water quantity is two times of the quantity of grape juice.
Now, we need to find the number of quarts of sparkling water need to mix in 9 quarts of grape juice.
<em>Since, sparkling water quantity is two times of the quantity of grape juice.</em>
<h3>Therefore, we need 2 × 9 = 18 quarts of sparkling water to mix in 9 quarts of grape juice.</h3>
And now we need to find the number of quarts of grape juice would we need to mix with 15/4 quarts of sparkling water.
<h3>Therefore, we need 1/2 × 15/4 = 15/8 quarts of grape juice to mix with 15/4 quarts of sparkling water.</h3>