Finding the Compound Inequality

Oct 13, 2025 by wbrum.org 0 views

Introduction

In this problem, we are given a scenario where Clara is growing her hair out and wants it to be no longer than 15 cm but more than 11 cm. Her hair is currently 7 cm long and grows at a rate of 0.25 cm per week. We need to find the compound inequality that models this scenario.

Understanding the Problem

Let's break down the problem step by step:

Clara wants her hair to be no longer than 15 cm, which means it should be less than or equal to 15 cm.
Clara wants her hair to be more than 11 cm, which means it should be greater than 11 cm.
Clara's hair is currently 7 cm long and grows at a rate of 0.25 cm per week.

Modeling the Scenario

Let $$t$$ be the time in weeks. We can model the length of Clara's hair after $$t$$ weeks as $$7 + 0.25t$$.

We want to find the compound inequality that represents the scenario. To do this, we need to consider the two conditions:

The length of Clara's hair should be less than or equal to 15 cm.
The length of Clara's hair should be greater than 11 cm.

We can write these conditions as inequalities:

7 + 0.25t \leq 15

and

7 + 0.25t > 11

Solving the Inequalities

Now, let's solve these inequalities to find the compound inequality that models the scenario.

Solving the First Inequality

7 + 0.25t \leq 15

Subtracting 7 from both sides gives:

0.25t \leq 8

Dividing both sides by 0.25 gives:

t \leq 32

Solving the Second Inequality

7 + 0.25t > 11

Subtracting 7 from both sides gives:

0.25t > 4

Dividing both sides by 0.25 gives:

t > 16

Finding the Compound Inequality

Now that we have solved the two inequalities, we can find the compound inequality that models the scenario.

The compound inequality is the intersection of the two inequalities:

16 < t \leq 32

This means that the time $$t$$ should be greater than 16 weeks and less than or equal to 32 weeks.

Conclusion

In this problem, we have modeled the scenario of Clara's hair growth using a compound inequality. We have found that the time $$t$$ should be greater than 16 weeks and less than or equal to 32 weeks for Clara's hair to be no longer than 15 cm but more than 11 cm.

Key Takeaways

We can model a scenario using a compound inequality by considering the intersection of multiple inequalities.
We can solve compound inequalities by finding the intersection of the individual inequalities.
We can use compound inequalities to model real-world scenarios that involve multiple conditions.

Practice Problems

A company wants to produce a product that weighs between 10 kg and 20 kg. The product is currently 5 kg and weighs 0.5 kg per hour. Find the compound inequality that models this scenario.
A student wants to score between 80% and 90% on a test. The student has scored 70% so far and scores 2% per hour. Find the compound inequality that models this scenario.

Answer Key

$10 < t \leq 30$
$8 < t \leq 20$$<br/>$

Introduction

In our previous article, we explored the scenario of Clara's hair growth and modeled it using a compound inequality. In this article, we will answer some frequently asked questions related to this topic.

Q: What is a compound inequality?

A: A compound inequality is a mathematical statement that combines two or more inequalities using logical operators such as "and" or "or". In the case of Clara's hair growth, we had two inequalities: $$t > 16$$ and $$t \leq 32$$, which we combined to form the compound inequality $$16 < t \leq 32$$.

Q: How do I solve a compound inequality?

A: To solve a compound inequality, you need to find the intersection of the individual inequalities. This means that you need to find the values of the variable that satisfy both inequalities. In the case of Clara's hair growth, we found that the time $$t$$ should be greater than 16 weeks and less than or equal to 32 weeks.

Q: What is the difference between a compound inequality and a single inequality?

A: A single inequality is a mathematical statement that compares a single expression to a constant or another expression. A compound inequality, on the other hand, combines two or more inequalities using logical operators. In the case of Clara's hair growth, we had a single inequality $$7 + 0.25t \leq 15$$, which we combined with another inequality $$7 + 0.25t > 11$$ to form a compound inequality.

Q: Can I use a compound inequality to model a scenario with more than two conditions?

A: Yes, you can use a compound inequality to model a scenario with more than two conditions. However, you need to be careful when combining multiple inequalities. You need to make sure that the logical operators are used correctly and that the inequalities are combined in a way that makes sense for the scenario.

Q: How do I graph a compound inequality?

A: To graph a compound inequality, you need to graph each individual inequality separately and then find the intersection of the two graphs. In the case of Clara's hair growth, we would graph the two inequalities $$t > 16$$ and $$t \leq 32$$ and find the intersection of the two graphs.

Q: Can I use a compound inequality to model a scenario with negative values?

A: Yes, you can use a compound inequality to model a scenario with negative values. However, you need to be careful when working with negative values and make sure that the inequalities are combined correctly.

Q: How do I use a compound inequality in real-world applications?

A: Compound inequalities can be used in a variety of real-world applications, such as:

Modeling population growth or decline
Predicting stock prices or other financial data
Analyzing data from scientific experiments
Solving problems in engineering or architecture

Conclusion

In this article, we have answered some frequently asked questions related to compound inequalities. We have discussed how to solve compound inequalities, how to graph them, and how to use them in real-world applications. We hope that this article has been helpful in understanding compound inequalities and how to use them to model real-world scenarios.

Practice Problems

A company wants to produce a product that weighs between 10 kg and 20 kg. The product is currently 5 kg and weighs 0.5 kg per hour. Find the compound inequality that models this scenario.
A student wants to score between 80% and 90% on a test. The student has scored 70% so far and scores 2% per hour. Find the compound inequality that models this scenario.
A population is growing at a rate of 2% per year. The population is currently 100,000 and will reach 150,000 in 10 years. Find the compound inequality that models this scenario.

Answer Key

$10 < t \leq 30$
$8 < t \leq 20$
$10 < t \leq 20$