How many liters of the 65% alcohol solution should be used?

Question

A chemist wants to mix a 65% alcohol solution with 10 liters of a 45% alcohol solution to produce a solution that is 55% alcohol. How many liters of the 65% alcohol solution should be used?

Answer 1

....................  liters     X percent  =  total alcohol in subtance

solution a:        x liters x (.65) = .65x

solution b:      10 liters x (.45) = 4.5

final solution: (x+10) x (.55) = .55x + 5.5

 

add solution a+b to get final solution 

.65x + 4.5 = .55x + 5.5

.10x = 1.0

x = 10

 

There were 10 liters of the 65% solution