A mixture of 9% disinfectant solution is to be made from 15% and 8% disinfectant solutions. How much of each solution should be used if 70 gallons of 9% solution are needed?
A)10 gallons at 15% solution, 60 gallons at 8% solution
B)58 gallons at 15% solution, 12 gallons at 8% solution
C)5 gallons at 15% solution, 65 gallons at 8% solution
D)12 gallons at 15% solution, 58 gallons at 8% solution
E)20 gallons at 15% solution, 50 gallons at 8% solution

Question

Quizplus · Accepted Answer

To solve this, we use the equation for mixture problems: (amount of first solution)(percentage of first solution) + (amount of second solution)(percentage of second solution) = (total amount of mixture)(percentage of mixture). Let x be the amount of 15% solution, then (70-x) is the amount of 8% solution. The equation becomes: 0.15x + 0.08(70-x) = 0.09(70). Solving for x gives 10 gallons of 15% solution and 70-10 = 60 gallons of 8% solution.

A Mixture of 9% Disinfectant Solution Is to Be Made