Salad dressing A is made up of 30% vinegar and 70% oil, and salad dres...
Let's assume that the quantity of dressing A used is x and the quantity of dressing B used is y to create the new dressing.
Since we are combining dressing A and dressing B to produce a dressing with 15% vinegar, we can set up the following equation based on the vinegar content:
(0.30 * x + 0.10 * y) / (x + y) = 0.15
Simplifying the equation:
0.30x + 0.10y = 0.15(x + y)
0.30x + 0.10y = 0.15x + 0.15y
0.30x - 0.15x = 0.15y - 0.10y
0.15x = 0.05y
3x = y
This means that the quantity of dressing B used (y) is three times the quantity of dressing A used (x).
To find the percentage of dressing A in the new dressing, we need to calculate the ratio of dressing A to the total dressing (A + B).
Percentage of dressing A = (x / (x + y)) * 100
Substituting y = 3x:
Percentage of dressing A = (x / (x + 3x)) * 100
Percentage of dressing A = (x / 4x) * 100
Percentage of dressing A = (1/4) * 100
Percentage of dressing A = 25%
Therefore, dressing A comprises 25% of the new dressing.
The correct answer is C: 25%.