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Percent Lesson 53

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The word percent can be broken down to determine its meaning. The word percent can be broken down to determine its meaning. per = bycent = one hundred Therefore, the word percent means by 100. The symbol for percent is %

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One percent of a number is one hundredth of the number. One percent of a number is one hundredth of the number. Therefore, 20 % means 20 parts of 100 or 20 hundredths. Therefore, 20 % means 20 parts of 100 or 20 hundredths.

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Percents have equivalents in both fractions and decimals 20% Percent.20 Decimal 20 100 Fraction 1515 Reduced = = =

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How to find a percent of a whole number Don’t forget that “of” means to multiply Don’t forget that “of” means to multiply ofx =

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How to find the percent of a whole number. Step 1 - When you see a percent problem you know when you read “of” in the problem you multiply. Step 1 - When you see a percent problem you know when you read “of” in the problem you multiply. 25% of 200

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Step 2 – Change your percent to a decimal and then move it two places to the left. Step 2 – Change your percent to a decimal and then move it two places to the left. 25% x 200

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Step 3 – Multiply just like a regular decimal multiplication problem. Step 3 – Multiply just like a regular decimal multiplication problem.

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Step 4 – Place the decimal point 2 places to the left in your answer. Step 4 – Place the decimal point 2 places to the left in your answer. 5000

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What is 20 % of 820?

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Example What is 40 % of 725?

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Example What is 60 % of 692? What is 60 % of 692?

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Example Sales tax is 5% in Maryland. Joey bought a pair of basketball shoes advertised for $62.00. How much sales tax did he pay? Sales tax is 5% in Maryland. Joey bought a pair of basketball shoes advertised for $62.00. How much sales tax did he pay?

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What does increase in % mean? What if you heard that the price of peanuts in Beijing went up 10% last year. If the old price was 60 yuan, what is the new price? What if you heard that the price of peanuts in Beijing went up 10% last year. If the old price was 60 yuan, what is the new price? What is 10% of 60 yuan? What is 10% of 60 yuan? 0.1 x 60 = 6 yuan ( this is the increase) 0.1 x 60 = 6 yuan ( this is the increase) Now add the increase to the old price: Now add the increase to the old price: 60 + 6 = 66 yuan 60 + 6 = 66 yuan

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Practice: Try this on your own! The number of acorns on the ground increased 240 percent during the storm. If 5400 acorns were on the ground before the storm, how many were on the ground after the storm? The number of acorns on the ground increased 240 percent during the storm. If 5400 acorns were on the ground before the storm, how many were on the ground after the storm? 240% x 5400 = b 2.4 x 5400 = 12960 12960 + 5400 = 18,360 acorns

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Percent of Increase To find a percent of increase, form a fraction with the amount of increase over the original amount, and change the fraction to a percent. To find a percent of increase, form a fraction with the amount of increase over the original amount, and change the fraction to a percent.

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Percent of Decrease To find the percent of decrease, follow the procedure for finding a percent of increase, but place the amount of decrease over the original amount. To find the percent of decrease, follow the procedure for finding a percent of increase, but place the amount of decrease over the original amount.

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Example In 2000, there were 240 eighth graders enrolled in Sachin’s school. In 2005, there were 336 eighth graders enrolled. What was the percent of increase in enrollment? In 2000, there were 240 eighth graders enrolled in Sachin’s school. In 2005, there were 336 eighth graders enrolled. What was the percent of increase in enrollment?

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Answer 1 st : find the amount of increase: 336-240 1 st : find the amount of increase: 336-240 2 nd : form a fraction 2 nd : form a fraction amt. of increase = 96 original amt. 240 original amt. 240 Change the fraction to a decimal Change the fraction to a decimal Change the decimal to a percent Change the decimal to a percent

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Example Zack Cole shot an 86 on the golf course on Monday. On Friday, he shot a 95. What is the % of change? Zack Cole shot an 86 on the golf course on Monday. On Friday, he shot a 95. What is the % of change?

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Homework 1 1. What is 1% of 24? 2. What is 56% of 24? 3. What is 1% of 3200? 4. What is 101% of 3200? 5. 75% of all the skateboarders at the competition could execute a kickflip. If 14 could not execute a kickflip, how many skateboarders were at the competition?

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Homework 2 1. The ratio of western movies to comedies at the video store was 7 to 9. If there were 210 westerns, how many comedies were there? 2. Thirty percent of what number is 123? 3. What percent of 39 is 24? 4. There are 130 mountain bikes at Ike’s Bikes bicycle shop. If 52 of the mountain bikes have bar ends, what percent of the bikes have bar ends?

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Homework 3 1. The number increased from 40 to 280. What % increase was this? 2. Jonathan Rogers drew 47 planes in 4 th period. He drew 28 in 5 th period. What is the % of change? 3. Matt Viers bought 42 CD’s last year. He bought only 35 this year. What is the % of change? 4. Last six weeks, Joseph Lawhorn made an 88. This six weeks he made a 92. Find the % of change.

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