Holt Mathematics Estimating With Percents Lesson 6-2 Challenge Answers

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2 -8 Percents Warm Up Lesson Presentation Lesson Quiz Holt Algebra 1

2 -8 Percents Warm Up Change each percent to a decimal. 1. 73% 0.

2 -8 Percents Warm Up Change each percent to a decimal. 1. 73% 0. 73 2. 112% 1. 12 3. 0. 6% 0. 006 4. 1% 0. 01 Change each fraction or mixed number to a decimal. 5. 0. 5 6. 0. 3 7. 0. 8 8. Solve each proportion. 9. Holt Algebra 1 12 10. 4. 2 1. 2

2 -8 Percents Objective Solve problems involving percents. Holt Algebra 1

2 -8 Percents Vocabulary percent Holt Algebra 1

2 -8 Percents A percent is a ratio that compares a number to 100.

2 -8 Percents A percent is a ratio that compares a number to 100. For example, To find the fraction equivalent of a percent write the percent as a ratio with a denominator of 100. Then simplify. To find the decimal equivalent of a percent, divide by 100. Holt Algebra 1

2 -8 Percents Some Common Equivalents Percent 10% 25% 40% 50% 60% 75% 80%100%

2 -8 Percents Some Common Equivalents Percent 10% 25% 40% 50% 60% 75% 80%100% Fraction Decimal The greatest percent shown in the table is 100% or 1. But percents can be greater than 100%. For example, 120% = = 1. 2. You can also find percents that are less than 1%. For example, 0. 5%= You can use the proportion unknown values. Holt Algebra 1 = = 0. 005. to find

2 -8 Percents Example 1 A: Finding the Part Find 30% of 80. Method

2 -8 Percents Example 1 A: Finding the Part Find 30% of 80. Method 1 Use a proportion. Use the percent proportion. Let x represent the part. 100 x = 2400 x = 24 30% of 80 is 24. Find the cross products. Since x is multiplied by 100, divide both sides by 100 to undo the multiplication. Check 30% is the same as Holt Algebra 1 , and of 80 is 24.

2 -8 Percents Example 1 B: Finding the Part Find 120% of 15. Method

2 -8 Percents Example 1 B: Finding the Part Find 120% of 15. Method 2 Use an equation. x = 120% of 15 x = 1. 20(15) x = 18 120% of 15 is 18. Holt Algebra 1 Write an equation. Let x represent the part. Write the percent as a decimal and multiply.

2 -8 Percents Check It Out! Example 1 a Find 20% of 60. Method

2 -8 Percents Check It Out! Example 1 a Find 20% of 60. Method 1 Use a proportion. Let x represent the part. 100 x = 1200 x = 12 20% of 60 is 12. Find the cross products. Since x is multiplied by 100, divide both sides by 100 to undo the multiplication. Check 20% is the same as Holt Algebra 1 , and of 60 is 12.

2 -8 Percents Check It Out! Example 1 b Find 210% of 8. Method

2 -8 Percents Check It Out! Example 1 b Find 210% of 8. Method 2 Use an equation. x = 210% of 8 x = 2. 10(8) x = 17 210% of 8 is 16. 8. Holt Algebra 1 Write an equation. Let x represent the part. Write the percent as a decimal and multiply.

2 -8 Percents Check It Out! Example 1 c Find 4% of 36. Method

2 -8 Percents Check It Out! Example 1 c Find 4% of 36. Method 2 Use an equation. x = 4% of 36 x = 0. 04(36) x =1. 44 4% of 36 is 1. 44. Holt Algebra 1 Write an equation. Let x represent the part. Write the percent as a decimal and multiply.

2 -8 Percents Example 2 A: Finding the Percent What percent of 45 is

2 -8 Percents Example 2 A: Finding the Percent What percent of 45 is 35? Round your answer to the nearest tenth. Method 1 Use a proportion. Use the percent proportion. Let x represent the percent. 45 x = 3500 Find the cross products. Since x is multiplied by 45, divide both sides by 45 to undo the multiplication. x ≈ 77. 8 35 is about 77. 8% of 45. Holt Algebra 1

2 -8 Percents Example 2 B: Finding the Percent 230 is what percent of

2 -8 Percents Example 2 B: Finding the Percent 230 is what percent of 200? Method 2 Use a equation. 230 = 200 x Write an equation. Let x represent the percent. Since x is multiplied by 200, divide both sides by 200 to undo the multiplication. 1. 15 = x The answer is a decimal. 230 = x 115% = x • 200 Write the decimal as a percent. This answer is reasonable; 230 is 115% of 200. more than 100% of 200. Holt Algebra 1

2 -8 Percents Check It Out! Example 2 a What percent of 35 is

2 -8 Percents Check It Out! Example 2 a What percent of 35 is 7? . Method 1 Use a proportion. Use the percent proportion. Let x represent the percent. 35 x = 700 x = 20 7 is 20% of 35. Holt Algebra 1 Find the cross products. Since x is multiplied by 35, divide both sides by 35 to undo the multiplication.

2 -8 Percents Check It Out! Example 2 b 27 is what percent of

2 -8 Percents Check It Out! Example 2 b 27 is what percent of 9? Method 2 Use an equation. Write an equation. Let x represent 27 = x • 9 the percent. 27 = 9 x Since x is multiplied by 9, divide both sides by 9 to undo the multiplication. The answer is a whole number. 3=x 300% = x 27 is 300% of 9. Holt Algebra 1 Write the whole number as a percent. This answer is reasonable; 27 is more than 100% of 9.

2 -8 Percents Example 3 A: Finding the Whole 38% of what number is

2 -8 Percents Example 3 A: Finding the Whole 38% of what number is 85? Round your answer to the nearest tenth. Method 1 Use a proportion. Use the percent proportion. Let x represent the whole. 38 x = 8500 x = 223. 7 Find the cross products. Since x is multiplied by 38, divide both sides by 38 to undo the multiplication. 38% of about 223. 7 is 85. Holt Algebra 1

2 -8 Percents Example 3 B: Finding the Whole 20 is 0. 4% of

2 -8 Percents Example 3 B: Finding the Whole 20 is 0. 4% of what number? Method 2 Use an equation. 20 = 0. 4% of x 20 = 0. 004 • x 5000 = x 20 is 0. 4% of 5000. Holt Algebra 1 Write an equation. Let x represent the whole. Write the percent as a decimal. Since x is multiplied by 0. 004, divide both sides by 0. 004 to undo the multiplication.

2 -8 Percents Check It Out! Example 3 a 120% of what number is

2 -8 Percents Check It Out! Example 3 a 120% of what number is 90? Method 1 Use a proportion. Use the percent proportion. Let x represent the whole. 120 x = 9000 x = 75 120% of 75 is 90. Holt Algebra 1 Find the cross products. Since x is multiplied by 120, divide both sides by 120 to undo the multiplication.

2 -8 Percents Check It Out! Example 3 b 48 is 15% of what

2 -8 Percents Check It Out! Example 3 b 48 is 15% of what number? Method 2 Use an equation. 48 = 15% of x Write an equation. Let x represent the whole. 48 = 0. 15 Write the percent as a decimal. • x 320 = x 48 is 0. 15% of 320. Holt Algebra 1 Since x is multiplied by 0. 15, divide both sides by 0. 15 to undo the multiplication.

2 -8 Percents Example 4: Application The serving size of a popular orange drink

2 -8 Percents Example 4: Application The serving size of a popular orange drink is 12 oz. The drink is advertised as containing 5% orange juice. How many ounces of orange juice are in one serving size? Use the percent proportion. Let x represent the percent. 100 x = 60 Since x is multiplied by 100, divide both sides by 100 to undo the multiplication. x = 0. 6 A 12 oz orange drink contains 0. 6 oz of orange juice. Holt Algebra 1

2 -8 Percents Check It Out! Example 4 Use the information above to find

2 -8 Percents Check It Out! Example 4 Use the information above to find the number of karats in a bracelet that is 42% gold. Round your answer to the nearest whole number. Use the percent proportion. Let x represent the number of karats. 100 x = 1008 Since x is multiplied by 100, divide both sides by 100 to undo the multiplication. x = 10. 08 A ring that contains 42% gold is about 10 karats. Holt Algebra 1

2 -8 Percents Lesson Quiz: Part 1 Find each value. Round to the nearest

2 -8 Percents Lesson Quiz: Part 1 Find each value. Round to the nearest tenth if necessary. 1. Find 20% of 80. 16 2. What percent of 160 is 20? 12. 5% 3. 35% of what number is 40? 114. 3 4. 120 is what percent of 80? 5. Find 320% of 8. 25. 6 6. 65 is 0. 5% of what number? Holt Algebra 1 150% 13, 000

2 -8 Percents Lesson Quiz: Part 2 Find each value. Round to the nearest

2 -8 Percents Lesson Quiz: Part 2 Find each value. Round to the nearest tenth if necessary. 7. A survey at a local school showed that 38% of the students chose chocolate ice cream as their favorite ice cream. Eight hundred students took the survey. How many chose chocolate ice cream? 304 Holt Algebra 1