Question

In chemistry you need to dilute an alcohol solution down. You have a 90% alcohol solution and a 20% alcohol solution. If you want to end up with 335L of 50% alcohol, how much of each do you need?

Answer 1

143.715 liters of 90% alcohol and 191.285 liters of 20% alcohol must be used to achieve 335 liters of 50% alcohol.

Explanation:

Since I need to dilute an alcohol solution down, and I have a 90% alcohol solution and a 20% alcohol solution, if I want to end up with 335L of 50% alcohol, to determine how much of each do I need to be perform the following calculation:

100 x 0.9 + 0 x 0.2 = 90

90 x 0.9 + 10 x 0.2 = 83

80 x 0.9 + 20 x 0.2 = 76

70 x 0.9 + 30 x 0.2 = 69

60 x 0.9 + 40 x 0.2 = 62

50 x 0.9 + 50 x 0.2 = 55

40 x 0.9 + 60 x 0.2 = 48

42 x 0.9 + 58 x 0.2 = 49.4

43 x 0.9 + 57 x 0.2 = 50.1

42.9 x 0.9 + 57.1 x 0.2 = 50

335 x 42.9 / 100 = 143.715

335 - 143,715 = 191,285

Thus, 143.715 liters of 90% alcohol and 191.285 liters of 20% alcohol must be used to achieve 335 liters of 50% alcohol.