Question

95. A 20-gallon alcohol-water solution contains 15% pure alcohol. How much alcohol should

be added to make a new solution that is 20% alcohol ?​

Answer 1

1.25 gallons of alcohol

Explanation:

Let x represent the amount of alcohol to add to the mix. Then the total amount of alcohol in the mix is ...

0.15×20 + x = 0.20×(20 +x)

3 +x = 4 + 0.2x . . . . simplify

0.8x = 1 . . . . . . . . . . add -3-0.2x

x = 1/0.8 = 1.25 . . . . divide by 0.8

1.25 gallons of alcohol should be added to make 21.25 gallons of 20% alcohol.