## Percent Error and Percent Increase

#### 7.RP.A.3 - Grade 7 Proportional Relationships

What Is Percentage Error and Percentage Increase? - Whether it's profit on a sale item, error in a critical lab reading, or changes in the trends of a business' revenue, people need tools that can help them determine the changes and identify the patterns in the trend. There is one way you can calculate it and that is through percentages. Percentages are very helpful and the two methods that can be used to describe these changes are percentage errors and percentage change (increase or decrease). Percentage Error - Percentage error is the quantity which helps in determining the difference between the experimental and theoretical value. Step 1: Calculate the difference between the theoretical and experimental value Error=Theoretical value-Experimental Value Step 2: Calculate the fractional change in the values Fractional Change=(Theoretical Value-Experimental Value)/(Theoretical Value) Step 3: Multiply the fractional change by 100 to find the percentage error Percentage Error=(theoretical Value-Experimental Value)/(Theoretical Value)×100 Percentage Increase - The percentage increase is the value that compares the new increased value with the previous value. It can be calculated just like the percentage error. Step 1: Calculate the difference between the new and old value Difference=New Value-Old Value Step 2: Calculate the Fractional increase in the old value Fractional Change=(New Value-Old Value)/(Old Value) Step 3: Multiply fractional change by 100 Fractional Change=(New Value-Old Value)/(Old Value)×100

### Printable Worksheets And Lessons  #### Homework Sheets

See if you can try to help students focus in on the relationship between both of these skills.

• Homework 1 - John needs to purchase a blanket for his bedroom. John measured the blanket as 6 ft. The actual measurement was 5.5 ft. What is John’s percent error?
• Homework 2 - Liza was asked by the farmer to count all the cows. He counted a total of 120 cows. Liza did make a mistake in counting the cows and recorded the number as 160. What is Liza percent error?
• Homework 3 - Emma sold a hat for \$20. Emma increases the price by 25%. What is the price of the hat now?

#### Practice Worksheets

Why are stores always increasing prices lately? Time to look at the math behind that.

• Practice 1 - Eva buys a guitar for \$325. The store increases its purchase price by 20%? What is the new price of the guitar?
• Practice 2 - Soul wants to buy a ring for his wife. Soul calculates the amount of ring as \$85.8. The actual price of ring is \$80. What is Soul’s percent error?
• Practice 3 - Alisa calculates the cost of color box as \$40. The actual price was \$48. What is her percent error?

#### Math Skill Quizzes

I also throw in percentages of total in here to act as a ladder skill.

• Quiz 1 - Calculate 3% of 52.4 meters?
• Quiz 2 - A serving of chocolates cookies contains 1600 calories. One hundred thirty-five calories comes from fat. What percent of the total calories come from fat?
• Quiz 3 - Helen buys a shirt for \$110. The store increases their purchase price by 25%? What is the new price?