You need 300 ml of a 60% alcohol solution. Onhand you have 50% alcohol mixture and a 75% alcohol mixture. How many of each mixture will you need to obtain the

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Answer 1

Set this up to give you a system of 2 equations in 2 unknowns x and y, and then solve the system.

 

x = required volume at 50%

y = required volume at 75%

 

Weighted combination of the 2 concentrations that gives 300 ml at 60% is

 

(50%)x + (75%)y = (60%)(300 ml)   [= 18,000]

x + y = 300 ml

 

Solve for x and y in

 

50x + 75y = 18,000

x + y = 300

 

You should get x = 180 ml, y = 120 ml