How many deciliters

Question

How many deciliters of alcohol  must be added to 100 deciliters of a 40% accohol solution to obtain a 50% sollution?

Answer 1

Let x = number of deciliters of pure alcohol

    100 = number of deciliters of 40% alcohol solution

x + 100 = number of deciliters of the mixture

 

1.00x + 0.40(100) = 0.50(x + 100)

 

       x + 40 = 0.50x + 50

 

            0.50x = 10

 

                   x = 20

 

Use 20 deciliters of pure alcohol and 100 deciliters of 40% solution to obtain 120 deciliters of the desired mixture.