MIXTURE PROBLEM

QUESTION

• How many liters of 9% salt solution must be added to a 15% salt solution to get 25L of 12% salt solution?

SOLUTION

Let L = liters

x = unknown variable

Equation 1:

• 12% of 25L = N
• 0.12 x 25L = 3L

Keep in mind that if we add a 9% solution to 15% salt solution , The result should be 3L.

Forming an equation to the given problem:

• 9%L + 15% (x) = 25L x 12%

Solution to the equation

• 9%L + 15%x = 25L x 12%
• 0.09L + 0.15x = 3L
• 0.15x = 3L - 0.09L
• 0.15x = 2.91
• x = 2.91 ÷ 0.15
• x = 19.4L

Checking:

• 9%L + 15%(19.4L) = 25L x 12%
• 0.09L + 2.91L = 25L x 0.12
• 3L = 3L ✔️

ANSWER

• 19.4 Liters should be added to get a 25L of 12% solution.

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