Question

Maki uses 20 gallons of a solution with an unknown ethanol concentration and 60 gallons of a 12% ethanol solution to make 80 gallons of a 10% solution. What is the value of x, the concentration of the unknown ethanol solution?.
a. 0.02.
b. 0.04.
c. 0.05.
d. 0.08

Answer 1

the correct answer is B

Answer 2

The equation is:
x * 20 + 0.12 * 60 = 0.10 * 80
20 x + 7.2 = 8
20 x = 8 - 7.2
20 x = 0.8
x = 0.8 : 20 = 0.04 ( or 4% )
Answer: B ) 0.04