Applications involving mixtures

Question

How much pure bleach should Tim combine with a solution that is 4% bleach to make 12 ounces of a 12% bleach solution?(hint: pure Bleach is 100% bleach

Answer 1

Amber:

 

Write two equations, one equation based on the number of ounces of solution and the second, the number of ounces of bleach

 

Let x = ounces of pure bleach added

 

Let y = ounces of 4% bleach solution

 

The number of ounces of solution:  x + y = 12

 

The number of ounces of bleach: 100% of x  + 4% of y equals 12% of 12

 

x + y = 12

 

x + .04y = .12(12)

 

 

x + y = 12

 

x + .04y = 1.44

 

Subtract the second equation from the first, leaving:

 

y - .04y = 10.56

 

.96y = 10.56

 

Multiply by 100 so 96y = 1056

 

Divide both sides by 96 so y = 11

 

If y = 11 ounces of 4% solution, then x = 1 ounce of pure bleach