Chapter 10: Problem 24
Five pounds of potatoes, 1 pound of onions, and 2 pounds of apples cost $$\$ 3.80$$. Two pounds of potatoes, 3 pounds of onions, and 4 pounds of apples cost $$\$ 5.78$$. Three pounds of potatoes, 4 pounds of onions, and 1 pound of apples cost $$\$ 4.08$$. Find the price per pound for each item.
Short Answer
Expert verified
Potatoes: $0.30, Onions: $0.58, Apples: $0.86 per pound.
Step by step solution
01
Define the Variables
Let's denote the price per pound of potatoes as \( p \), the price per pound of onions as \( o \), and the price per pound of apples as \( a \).
02
Write the System of Equations
Using the provided information, set up the system of equations based on the cost of the items:1. \( 5p + 1o + 2a = 3.80 \)2. \( 2p + 3o + 4a = 5.78 \)3. \( 3p + 4o + 1a = 4.08 \)
03
Eliminate One Variable
We will use the elimination method to remove one variable. Start by eliminating \( a \). Multiply the first equation by 2 and the second equation by 1 (no change needed) and subtract:\[(10p + 2o + 4a = 7.60) - (2p + 3o + 4a = 5.78) \]This results in: \( 8p - o = 1.82 \).
04
Continue the Elimination Process
Now eliminate \( a \) using equations 2 and 3. Multiply equation 3 by 4 and subtract equation 2:\[(12p + 16o + 4a = 16.32) - (2p + 3o + 4a = 5.78) \]This gives: \( 10p + 13o = 10.54 \).
05
Solve the Two-Variable System
Now we have a simpler system:1. \( 8p - o = 1.82 \)2. \( 10p + 13o = 10.54 \)Solve for \( o \) from the first equation: \( o = 8p - 1.82 \). Substitute this in the second equation:\[10p + 13(8p - 1.82) = 10.54 \]Simplify and solve: \( 10p + 104p - 23.66 = 10.54 \), leading to \( 114p = 34.20 \), thus \( p = 0.30 \).
06
Find the Remaining Variables
Use \( p = 0.30 \) to find \( o \) from \( o = 8p - 1.82 \):\[o = 8(0.30) - 1.82 = 0.58 \]Use one of the original equations to find \( a \). Use \( 5p + o + 2a = 3.80 \) with the known values and solve for \( a \):\[5(0.30) + 0.58 + 2a = 3.80 \]\[1.50 + 0.58 + 2a = 3.80 \]\[2.08 + 2a = 3.80 \]\[2a = 1.72 \], \( a = 0.86 \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Price per Pound Calculation
Calculating the price per pound of a particular item involves determining the cost for a single unit of weight—typically, a pound. This is useful when you're given a total cost for multiple items and want to find out how much one unit of a specific item costs. To solve such problems, we often gather various combinations of these items with given costs, as seen in the provided exercise.
- The key is to set up a system of equations based on the data you have, which represents different combinations of items with their total cost.
- By solving these equations, you can determine the price per pound for each individual item.
Elimination Method in Algebra
The elimination method in algebra is a powerful tool for solving systems of linear equations. It involves strategically adding or subtracting equations in a system to eliminate one of the variables. This makes it easier to solve for the remaining variables.
- The goal is to manipulate the equations so that when you add or subtract them, one variable cancels out.
- In our example, we started by trying to remove the variable representing apples (\( a \)).
Solving Linear Equations
Solving linear equations means finding the values of variables that make the equation true. These types of equations allow us to model real-world relationships where variables are linearly proportional to each other.
- The process typically involves isolating the variable you are solving for on one side of the equation.
- For the problem given, once we had our simplified system of equations, solving them involved typical algebraic operations—such as addition, multiplication, and substitution.