Chapter 7-4 Using Percent Proportions Unit 3 Chapter 7-4 Using Percent Proportions prealgebrateachers.com

Key Concept In a percent proportion, one of the numbers is called the PART. The PART is being comparted to a whole quantity called the BASE. The other ratio is the percent, written as a fraction, whose base is 100. 𝑝𝑎𝑟𝑡 𝑏𝑎𝑠𝑒 = 𝑝𝑒𝑟𝑐𝑒𝑛𝑡 100 or 𝑎 𝑏 = 𝑝 100 or 𝑖𝑠 𝑜𝑓 = 𝑝 100 where a is the part, b is the base, and p is the percent prealgebrateachers.com

Types of Percent Problems Example Proportion Find the percent 5 is WHAT PERCENT of 9? 5 9 = 𝑝 100 Find the Part What Number is 75% of 4? 𝑎 4 = 75 100 Find the Base 3 is 45% of What Number? 3 𝑏 = 45 100 prealgebrateachers.com

Find the percent Five is what percent of 10? Five is being compared to 10. So, 5 is the part and 10 is the base. Let p represent the percent. 5 10 = 𝑝 100 5 •100= 10•p 500 10 = 10𝑝 10 50% = p SO 5 is 50% of 10 prealgebrateachers.com

Find the Percent What percent of 4 is 7? Seven is being compared to 4, so 7 is the part and 4 is the base. Let p represent the percent. 7 4 = 𝑝 100 7•100=4•p 700 4 = 4𝑝 4 175% = P so 175% of 4 is 7. prealgebrateachers.com

Find the part What number is 8% of 75? The percent is 8% and the base is 75. Let a represent the part. 𝑎 75 = 8 100 100•a=75•8 100𝑎 100 = 600 100 a = 6 so 6 is 8% of 75 prealgebrateachers.com

Find the base 19 is 10% of what number? The percent is 10% and 19 is the part. Let b represent the base. 19 𝑏 = 10 100 19•100=10•b 1900 10 = 10𝑏 10 b = 190 so 19 is 10% of 190 prealgebrateachers.com

Let’s Try Some Examples! Find the percent Twelve is what percent of 16? Find the part or the base 2) What number is 2.5% of 15? 3) 225 is 36% of what number? prealgebrateachers.com

Let’s Check Our Answers Find the percent Twelve is what percent of 16? 12 16 = 𝑝 100 p =75% Find the part or the base 2) What number is 2.5% of 15? 3) 225 is 36% of what number? 𝑎 15 = 2.5 100 225 𝑏 = 36 100 a = .375 b = 625 prealgebrateachers.com