1. Chapter 7-4 Using Percent Proportions
Unit 3
Chapter 7-4 Using Percent Proportions
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2. 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 or 𝑎 𝑏 = 𝑝 or 𝑖𝑠 𝑜𝑓 = 𝑝 100
where a is the part,
b is the base, and p is the percent
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3. 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 =
Find the Base
3 is 45% of What Number?
3 𝑏 =
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4. 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
= 10𝑝 10
50% = p SO 5 is 50% of 10
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5. 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.
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6. 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 =
a = 6 so 6 is 8% of 75
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7. 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 = •100=10•b = 10𝑏 10 b = 190 so 19 is 10% of 190
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8. 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?
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9. 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 = 𝑏 =
a = b = 625
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