NOTES: Name: _____________________________ Date: ___________ Period:_______ Learning Targets Chapter 5: Day 4 Percent Increase & Decrease I can solve problems involving percent increase and decrease. I can persevere. Percent increase and percent decrease are measures of __________________________, which is when something ___________________ or ____________________ value. Percent changes are useful to help people understand changes in a value over time. Example: Jackie bought a pair of shoes for $52.00. At the register, she was told there would be $2.60 in sales tax. What percent of the original was the sales tax? (Start by writing a number sentence) What kinds of words could be used to represent a percent increase, decrease or change? When given two numbers and asked to find the percent change, we can use this formula: |𝑁𝑒𝑤 𝑉𝑎𝑙𝑢𝑒 − 𝑂𝑙𝑑 𝑉𝑎𝑙𝑢𝑒|
∙ 100 = 𝑃𝑒𝑟𝑐𝑒𝑛𝑡 𝐶ℎ𝑎𝑛𝑔𝑒 𝑂𝑙𝑑 𝑉𝑎𝑙𝑢𝑒
***Quick reminder, what do the bars on the formula mean? Problem
Subtraction
Division
Percent
Answer
Increase or
Decrease?
From 5 to 45 From 100 to 30 Chapter 5 Day 4 Student Notes p. 1 Examples: Find each answer then classify as either a percent increase or decrease. 1. Dennis bought an antique model train for $64. Two years later, he sold it for $72. What was the percent increase in the price of the model train? Percent Increase Percent Decrease 2. Alan deposited $300 dollars into a savings account. At the end of the first year, the amount of money in the account had increased to $336. At the end of the second year, he had $420. a. Find the change from the first year to the second year? Percent Increase Percent Decrease b. What about the second year to the third year? 3. The original price of a computer was $1,250. At a year-­‐end sale, the selling price of the computer was $900. Find the precent discount. Percent Increase Percent Decrease 4. Tom earned $600 last summer delivering news papers. This summer, he earned 20% more. How much did he earn this summer? Percent Increase Percent Decrease 5. Last year, Alex earned a monthly salary of $250, and Ben earned a monthly salary salary of $180. This year, each of them received a pay increase of 25%. This year, how much more did Alex earn in one month than Ben? Percent Increase Chapter 5 Day 4 Student Notes p. 2 Percent Decrease