Percent Of Increase Word Problems

Mastering Percent of Increase Word Problems: A Comprehensive Guide

Understanding percent of increase is a crucial skill applicable in various real-life situations, from calculating salary raises and price hikes to analyzing market trends and population growth. This comprehensive guide will equip you with the knowledge and strategies to confidently tackle any percent of increase word problem. We'll delve into the fundamental concepts, provide step-by-step solutions to various problem types, and explore the underlying mathematical principles. By the end, you'll not only be able to solve these problems but also understand the logic behind them.

Understanding the Fundamentals: What is Percent Increase?

Percent increase refers to the relative change in a quantity, expressed as a percentage. It indicates how much a value has grown compared to its original value. The calculation involves finding the difference between the new value and the original value, then expressing this difference as a percentage of the original value. Think of it as measuring the growth relative to the starting point.

Key Terms:

• Original Value (Initial Value): The starting value or amount before the increase.
• New Value (Final Value): The value after the increase has been applied.
• Increase: The difference between the new value and the original value (New Value - Original Value).
• Percent Increase: The increase expressed as a percentage of the original value.

Step-by-Step Approach to Solving Percent Increase Word Problems

A structured approach is essential for effectively solving percent increase problems. Here's a five-step method you can apply to any problem:

Step 1: Identify the Original Value and the New Value. Carefully read the problem to identify the initial amount and the amount after the increase. Clearly label these values.

Step 2: Calculate the Increase. Subtract the original value from the new value to find the difference (Increase = New Value - Original Value).

Step 3: Calculate the Percent Increase. Divide the increase by the original value and multiply the result by 100% to express it as a percentage. The formula is:

Percent Increase = [(New Value - Original Value) / Original Value] × 100%

Step 4: Check your Answer. Review your calculations to ensure accuracy. Does your answer make logical sense within the context of the problem?

Step 5: State Your Answer Clearly. Write your final answer in a complete sentence, including the units (if applicable).

Illustrative Examples: Solving Diverse Percent Increase Problems

Let's apply this five-step method to a variety of word problems to solidify your understanding.

Example 1: Simple Percent Increase

Problem: A shirt originally cost $25. The price increased to $30. What is the percent increase in the price?

Solution:

1. Original Value: $25
2. New Value: $30
3. Increase: $30 - $25 = $5
4. Percent Increase: ($5 / $25) × 100% = 20%
5. Answer: The price of the shirt increased by 20%.

Example 2: Percent Increase with Larger Numbers

Problem: The population of a city was 150,000 in 2010. In 2020, the population grew to 180,000. Calculate the percent increase in population.

Solution:

1. Original Value: 150,000
2. New Value: 180,000
3. Increase: 180,000 - 150,000 = 30,000
4. Percent Increase: (30,000 / 150,000) × 100% = 20%
5. Answer: The city's population increased by 20%.

Example 3: Finding the New Value given the Percent Increase

Problem: A house was valued at $200,000. Its value increased by 15%. What is the new value of the house?

Solution: This problem requires a slightly different approach.

1. Original Value: $200,000
2. Percent Increase: 15%
3. Calculate the Increase: (15/100) * $200,000 = $30,000
4. New Value: $200,000 + $30,000 = $230,000
5. Answer: The new value of the house is $230,000. Alternatively, you can calculate the new value directly by multiplying the original value by 1 + (percent increase/100). In this case: $200,000 * (1 + 0.15) = $230,000

Example 4: Real-world Application – Salary Increase

Problem: Sarah's annual salary was $50,000. She received a 7% raise. What is her new annual salary?

Solution:

1. Original Value: $50,000
2. Percent Increase: 7%
3. Calculate the Increase: (7/100) * $50,000 = $3,500
4. New Value: $50,000 + $3,500 = $53,500
5. Answer: Sarah's new annual salary is $53,500.

Example 5: Problem Solving with Multiple Increases

Problem: A store increased the price of a toy by 10%, then later increased the new price by another 5%. If the original price was $10, what is the final price?

Solution: This involves a two-step calculation.

1. First Increase: 10% of $10 = $1. New price: $10 + $1 = $11
2. Second Increase: 5% of $11 = $0.55. Final price: $11 + $0.55 = $11.55
3. Answer: The final price of the toy is $11.55. Note that this is not a 15% increase from the original price.

Understanding the Mathematics Behind Percent Increase

The formula for percent increase is derived from the concept of relative change. The increase is expressed as a fraction of the original value. Multiplying this fraction by 100% converts it into a percentage. This emphasizes the proportional relationship between the increase and the initial amount. Understanding this underlying mathematical principle helps in tackling more complex problems.

Frequently Asked Questions (FAQ)

Q1: What if the value decreases instead of increases?

A1: If the value decreases, you're dealing with a percent decrease. The calculation is similar, but you subtract the new value from the original value, and the result will be negative. The absolute value of the result, when expressed as a percentage, represents the percent decrease.

Q2: How do I handle problems with multiple percent increases or decreases?

A2: For multiple percentage changes, you must calculate each change sequentially. Do not simply add the percentages together; this is incorrect. Calculate the new value after each change before applying the next percentage change.

Q3: Can I use a calculator for these problems?

A3: Absolutely! Calculators are highly recommended, especially for problems with larger numbers or multiple steps.

Q4: What are some real-world applications of percent increase?

A4: Many! From calculating interest earned on savings accounts and investments, to analyzing economic growth, tracking inflation rates, and understanding population changes, percent increase is a vital tool for interpreting data and making informed decisions.

Conclusion: Mastering the Art of Percent Increase

Solving percent increase word problems involves a systematic approach. By understanding the fundamental concepts, applying the step-by-step method, and practicing with various examples, you can develop confidence and proficiency in this essential mathematical skill. Remember to always clearly define your original and new values, carefully calculate the increase, and express the result as a percentage of the original value. With consistent practice, you'll master the art of solving percent increase word problems and apply this valuable skill to numerous real-world scenarios. Remember to always double-check your work and strive for a clear understanding of the underlying mathematical principles. This will not only improve your problem-solving skills but also foster a deeper appreciation for the practical application of mathematics.