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Your math instructor brings two opaque jars of candies to class one day. All the candies are red mints or green mints. The first jar contains 15 candies; the second jar contains 40 candies. Suppose the second jar contains twice as many red mints as the first jar, and three times as many green mints as the first jar. Determine how many mints of each color are in the two jars.

Short Answer

Expert verified
First jar: 5 red, 10 green. Second jar: 10 red, 30 green.

Step by step solution

01

Define Variables

Let \( r_1 \) and \( g_1 \) represent the number of red and green mints in the first jar, respectively. Similarly, let \( r_2 \) and \( g_2 \) represent the number of red and green mints in the second jar, respectively.
02

Write Equations for Total Mints

Based on the problem description, we have the following equations:\[ r_1 + g_1 = 15 \] (first jar total candies) and \[ r_2 + g_2 = 40 \] (second jar total candies).
03

Relate Red Mints in Jars

According to the problem, the second jar has twice as many red mints as the first jar, leading to the equation:\[ r_2 = 2r_1. \]
04

Relate Green Mints in Jars

It's also given that the second jar contains three times as many green mints as the first jar, leading to:\[ g_2 = 3g_1. \]
05

Substitute Known Relationships into Equations

Substitute \( r_2 = 2r_1 \) and \( g_2 = 3g_1 \) into the equation for the second jar:\[ 2r_1 + 3g_1 = 40. \]
06

Solve the System of Equations

We now have two equations:1. \( r_1 + g_1 = 15 \)2. \( 2r_1 + 3g_1 = 40 \).Solve the first equation for one variable: \( g_1 = 15 - r_1 \).Substitute \( g_1 = 15 - r_1 \) into the second equation:\[ 2r_1 + 3(15 - r_1) = 40. \]Simplify and solve:\[ 2r_1 + 45 - 3r_1 = 40 \]\[ -r_1 + 45 = 40 \]\[ -r_1 = -5 \]\[ r_1 = 5. \]
07

Find the Number of Green Mints in the First Jar

Substitute \( r_1 = 5 \) back into \( g_1 = 15 - r_1 \):\[ g_1 = 15 - 5 = 10. \]
08

Find the Number of Mints in the Second Jar

Use \( r_2 = 2r_1 \) and \( g_2 = 3g_1 \):\[ r_2 = 2 \times 5 = 10 \]\[ g_2 = 3 \times 10 = 30. \]
09

Verify the Solution

Check the conditions:- First jar: \( r_1 + g_1 = 5 + 10 = 15 \), which matches.- Second jar: \( r_2 + g_2 = 10 + 30 = 40 \), which matches.- Mints ratios: second jar has double the reds and triple the greens compared to the first, matching the conditions of the problem.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

System of equations
When solving problems involving relationships between different unknowns, the system of equations approach is often used. In our candy jar example, each jar holds a specific number of candies, but we need to figure out the quantities of different types (red and green mints) based on the problem constraints. To tackle this:
  • First, translate the scenario into algebraic expressions, where you've defined each mint color in each jar using variables.
  • Establish a set of simultaneous equations that describe the relationships and constraints given in the problem.
For example, the first jar has 15 candies, mathematically shown as \( r_1 + g_1 = 15 \), with \( r_1 \) and \( g_1 \) indicating the number of red and green mints, respectively. The second condition concerning the jars, \( r_2 + g_2 = 40 \), portrays the same concept with different values. Solving such a system requires either substitution or elimination techniques, which help isolate each variable and find its value.
This method not only helps in finding the number of mints of each color but also ensures all conditions of the problem have been met and checked for consistency.
Variables and expressions
Variables serve as placeholders for unknown quantities, allowing us to express complex relationships and constraints mathematically with ease. In our problem, variables like \( r_1, g_1, r_2, \) and \( g_2 \) represent the unknown counts of red and green mints in two jars. By using variables, we could write expressions and equations that capture the specifics of the problem. For instance, equations like \( r_2 = 2r_1 \) indicate the relationship between the mints in jars, transforming descriptive text into mathematical sentences.
This transformation is vital, as it allows us to apply algebraic techniques to solve for these variables, revealing the quantities hidden within the problem.
  • By representing values with variables, we maintain flexibility to substitute and manipulate these representations.
  • Expressions are built around these variables to establish conditions like total counts and relational ratios, which guides us toward solutions.
Understanding and applying variables effectively is a fundamental skill in solving algebraic word problems, turning abstract concepts into tangible numbers.
Word problems
Word problems are real-world scenarios presented in narrative form that require translation into mathematical language. They often challenge learners to discern relevant information and mathematically model the situation to solve it. Solving word problems, such as our jar problem, involves several steps:
  • First, read the situation carefully to identify key information and what the problem is asking you to find.
  • Next, define the unknowns using variables suitably, as we did with different color mints.
  • Lastly, write down the equations that reflect the relationships stated in the problem and solve them using algebraic methods like substitutions.
Word problems help develop critical thinking and problem-solving skills as they require you to break down complex scenarios into solvable parts. This is particularly handy in many fields where applications of algebra are discovered in everyday contexts. Beyond purely mathematical skills, tackling word problems hones the ability to interpret real-life situations with quantitative reasoning.

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