Chapter 2: Problem 58
Solve each of Problems by setting up and solving an appropriate algebraic equation. How many gallons of a \(12 \%\)-salt solution must be mixed with 6 gallons of a \(20 \%\)-salt solution to obtain a \(15 \%\)-salt solution?
Short Answer
Expert verified
10 gallons of the 12% solution are needed.
Step by step solution
01
Understand the Problem
We need to find out how many gallons of a 12% salt solution need to be mixed with 6 gallons of a 20% salt solution to create a solution that is 15% salt.
02
Define the Variables
Let \( x \) represent the number of gallons of the 12% salt solution needed.
03
Set Up the Equation
The total amount of salt in the mixture is equal before and after mixing. The equation is based on this principle: \(0.12x + 0.20 \times 6 = 0.15(x + 6)\).
04
Simplify and Solve the Equation
Expand and simplify the equation:1. \(0.12x + 1.2 = 0.15x + 0.9\)2. Subtract \(0.12x\) from both sides: \(1.2 = 0.03x + 0.9\)3. Subtract 0.9 from both sides: \(0.3 = 0.03x\)4. Divide both sides by 0.03: \(x = 10\).
05
Verify the Solution
Substitute \(x = 10\) back into the context of the problem. Mixing 10 gallons of 12% solution with 6 gallons of 20% solution gives:- Total salt from 12%: \(0.12 \times 10 = 1.2\) gallons- Total salt from 20%: \(0.20 \times 6 = 1.2\) gallons- Combined, the solution is 1.2 + 1.2 = 2.4 gallons of salt, in \(10 + 6 = 16\) gallons total.- The resulting concentration is \(\frac{2.4}{16} = 0.15\) or 15%.The solution checks out.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Mixture Problems
Mixture problems are a common type of algebraic puzzle where you combine different substances to reach a desired property or concentration. In many cases, like our problem, we're blending solutions with differing percentages of a substance to obtain a new solution with a specific percentage concentration. Understanding the structure of mixture problems involves considering different components and their proportions.
- Identify what is being mixed—here, solutions with salt concentrations.
- Define what the desired property of the final mixture should be—a 15% salt solution.
- Understand the relationships between the components and their contributions to the mixture.
Percentage Concentration
Percentage concentration is an important concept when dealing with solutions, as it quantifies the amount of a solute in a given amount of solution. In the case of salt solutions, you're often given a percentage which tells you what fraction of the solution is made up of salt. This is crucial in problems where we need to mix solutions to achieve a particular concentration.
- An understanding of what each percentage represents is necessary. For example, a 12% salt solution contains 12 grams of salt per 100 grams of solution.
- In our problem, we find how the individual concentrations contribute to the final mix by converting percentages into equations, like converting 12% into 0.12 in the equation.
- Calculating both before the mixture and after the expected outcome gives clarity on the constancy of the total solute in the process, emphasizing conservation principles.
Problem-Solving in Algebra
Approaching problem-solving in algebra, especially for mixture equations, requires a structured approach. This involves more than just applying formulas; it requires logically arranging the given information and variables.
- Start by clearly defining your variables, like using \(x\) for the unknown quantity.
- Set up equations based on the relationships between the variables, often representing contributions from each part of the mixture.
- Simplify and solve the equation methodically. First, expand the terms if needed, then move terms involving the variable you're solving for one side and constants to the other.
- Verification is key; after calculative processes, substitute back into the original framework to confirm accuracy. This ensures that the constructed solution adheres to the original problem statement.