Latest TCS Aptitude Question SOLUTION: In what proportions should a solution of 95%, 80%, 60% and 50% acid be mixed to produce a solution of 70% acid? a. 4 : 1 : 1 : 5 b. 4 : 2 : 1 : 5 c. 4 : 3 : 1 : 5 d. 4 : 1 : 2 : 5