Grade 7: Percent Change: A Simple Explanation

Understanding Percent Change 📈

Percent change helps us see how much something has increased or decreased. It's a way to express the change in a quantity as a percentage of the original amount. This is super useful in many real-life situations, like calculating price discounts, population growth, or changes in test scores.

The Percent Change Formula 📝

Here's the formula to calculate percent change:

Percent Change = [(New Value - Original Value) / Original Value] * 100

Let's break it down:

• New Value: The final amount.
• Original Value: The starting amount.

Calculating Percent Increase ⬆️

If the new value is greater than the original value, it's a percent increase.

Example:

Suppose a store sells a video game for $40 (original price). Due to demand, the price increases to $50 (new price). What is the percent increase?

Percent Change = [(50 - 40) / 40] * 100
Percent Change = [10 / 40] * 100
Percent Change = 0.25 * 100
Percent Change = 25%

So, the price of the video game increased by 25%.

Calculating Percent Decrease ⬇️

If the new value is less than the original value, it's a percent decrease.

Example:

A jacket originally cost $80. It goes on sale for $60. What is the percent decrease?

Percent Change = [(60 - 80) / 80] * 100
Percent Change = [-20 / 80] * 100
Percent Change = -0.25 * 100
Percent Change = -25%

The negative sign indicates a decrease. So, the price of the jacket decreased by 25%.

More Examples to Practice With ➕

1. Test Scores: You scored 70 on your last math test, and this time you scored 84. What's the percent increase?

   Percent Change = [(84 - 70) / 70] * 100 = 20%

   Your test score increased by 20%.

2. Population: A town had a population of 1200 people last year. This year, the population is 1140. What's the percent decrease?

   Percent Change = [(1140 - 1200) / 1200] * 100 = -5%

   The town's population decreased by 5%.

Why is Percent Change Important? 🤔

Understanding percent change helps you make informed decisions in everyday life. Whether you're comparing prices, tracking your grades, or analyzing data, knowing how to calculate percent change is a valuable skill!