Shanice wants to make a 72% alcohol solution. She has already poured 2 L of pure water into a beaker. How many L of a 90% alcohol solution must she add to this to create the desired mixture?

8 Liters

Step-by-step explanation:

Percentage of Alcohol in water = 2L X 0 = 0

Percentage of Alcohol to be added = xL X 0.9 = 0.9x

New Volume = (x+2) Liters Desired Concentration = 0.72%

Therefore:

0+0.9x=0.72 (x+2)

0.9x=0.72x+1.44

Collect like terms

0.9x-0.72x=1.44

0.18x=1.44

Divide both sides by 1.44

x=8 Liters

Therefore, Shanice must add 8 Liters of 90% alcohol solution to create the desired mixture