Answer:
495 milliliters of the 95% mixture are needed.
Step-by-step explanation:
Given that I need a 90% alcohol solution, and on hand I have a 55 ml of a 45% alcohol mixture, and I also have 95% alcohol mixture, to determine how much of the 95% mixture will I need to add to obtain the desired solution, the following calculation must be performed:
55 x 0.45 + 45 x 0.95 = 67.5
25 x 0.45 + 75 x 0.95 = 82.5
15 x 0.45 + 85 x 0.95 = 87.5
10 x 0.45 + 90 x 0.95 = 90
10 = 55
90 = X
90 x 55/10 = X
4,950 / 10 = X
495 = X
Thus, 495 milliliters of the 95% mixture are needed.
