Question

You need a 65% alcohol solution. On hand, you have a 50 mL of a 30% alcohol mixture. You also have 70% alcohol mixture. How much of the 70% mixture will you need to add to obtain the desired solution?
You will need
____________ mL of the 70% solution

Answer 1

Answer:

  350 mL

Step-by-step explanation:

Let q represent the quantity (in mL) needed of the 70% solution. Then the total amount of mixture will be q+50 milliliters. The total amount of alcohol in the mixture will be ...

  0.70q +0.30(50) = 0.65(50 +q)

  .05q = 17.5 . . . . . . subtract (0.65q +1.50)

  q = 350 . . . . . . . . . divide by 0.05

You will need 350 mL of the 70% solution.