Answer: Ted needs 1.875 cups of pretzels to make 15 cups of trail mix
Explanation:
He mixes 1 1/2 cups of nuts, 1/4 cup of raisins, and 1/4 cup of pretzels. This means that the ratio of ratio of the number of cups of nuts used to the number of cups of raisins used to the number of cups of pretzels used is
1.5 : 0.25 : 0.25
The total ratio is
1.5 + 0.25 + 0.25 = 2
Ted need to make 15 cups of trail mix. Therefore, the number of cups of pretzels that he needs to use is
0.25/2 × 15 = 1.875 cups of pretzels