Question

How much pure alcohol should be added to a 360 ml of a 30% alcohol solution to raise the concentration to 40%?

please help lol

Answer 1

60 mL

Explanation:

Let x represent the amount of pure alcohol to be added (in mL). The total amount of alcohol in the mix is ...

30% × 360 mL + 100% × x mL = 40% × (x +360) mL

108 + x = 0.4x + 144 . . . . simplify

0.6x = 36 . . . . . . . . . . . . . subtract 0.4x +108

36/0.6 = x = 60 . . . . . . . . divide by the coefficient of x

60 mL of pure alcohol must be added to 360 mL of 30% to raise the concentration to 40%.