Question 626508
Solution A
Amount = x ml
Concentration = 31% = 0.31


Solution B
Amount = 6 ml
Concentration = 11% = 0.11


Mixture
Amount = 6+x ml
Concentration = 21% = 0.21


(Amount of Solution A)*(Concentration of Solution A)+ (Amount of Solution B)*(Concentration of Solution B)=(Amount of Mixture)*(Concentration of Mixture)
(x)*(0.31)+ (6)*(0.11)=(6+x)*(0.21)
0.31x+0.66=1.26+0.21x
0.31x-0.21x=1.26-0.66
0.1x=0.6
0.1x/0.1=0.6/0.1
x=6



6ml of a 31% alcohol solution must be added to 6 ml of a 11% alcohol solution to produce 12ml of a 21% alcohol solution.