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Preview. Warm Up. California Standards. Lesson Presentation. 1. 3. 33. %. Warm Up 1. What percent of 20 is 18? 2. What percent of 400 is 50? 3. 9 is what percent of 27? 4. 25 is what percent of 4?. 90%. 12.5%. 625%. California Standards.
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Preview Warm Up California Standards Lesson Presentation
1 3 33 % Warm Up 1.What percent of 20 is 18? 2. What percent of 400 is 50? 3. 9 is what percent of 27? 4. 25 is what percent of 4? 90% 12.5% 625%
California Standards NS1.3 Convert fractions to decimals andpercents and use these representations in estimations, computations, andapplications.
When one number is known, and its relationship to another number is given by a percent, the other number can be found.
60 0.12 0.12 = n 0.12 Additional Example 1: Finding a Number When the Percent Is Known 60 is 12% of what number? Choose a method: Set up an equation. part = percent whole Set up an equation. 60 = 12% n Let n represent the whole. 60 = 0.12n 12% = 0.12 Divide both sides by 0.12. 500 = n Simplify. 60 is 12% of 500.
75 0.25 0.25 = n 0.25 Check It Out! Example 1 75 is 25% of what number? Choose a method: Set up an equation. part = percent whole Set up an equation. 75 = 25% n Let n represent the whole. 75 = 0.25n 25% = 0.25 Divide both sides by 0.25. 300 = n Simplify. 75 is 25% of 300.
Set up a proportion. = 85 17 100 n Additional Example 2: Application Anna earned 85% on a test by answering 17 questions correctly. If each question was worth the same amount, how many questions were on the test? Choose a method: Set up a proportion. Think: 85 is to 100 as 17 is to what number? 85 n = 100 17Find the cross products. 85n = 1700 Simplify.
85n = 1700 85 85 Additional Example 2 Continued Anna earned 85% on a test by answering 17 questions correctly. If each question was worth the same amount, how many questions were on the test? Divide both sides by 85. n = 20 Simplify. There were 20 questions on the test.
Set up a proportion. = 80 20 100 n Check It Out! Example 2 Tom earned 80% on a test by answering 20 questions correctly. If each question was worth the same amount, how many questions were on the test? Choose a method: Set up a proportion. Think: 80 is to 100 as 20 is to what number? 80 n = 100 20Find the cross products. 80n = 2000 Simplify.
80n = 2000 80 80 Check It Out! Example 2 Continued Tom earned 80% on a test by answering 20 questions correctly. If each question was worth the same amount, how many questions were on the test? Divide both sides by 80. n = 25 Simplify. There were 25 questions on the test.
55 5.2 Set up a proportion. = 100 h Additional Example 3A: Life Science Application When a giraffe is born, it is approximately 55% as tall as it will be as an adult. If a baby giraffe is 5.2 feet tall when it is born, how tall will it be when it is full grown, to the nearest tenth of a foot? Choose a method: Set up a proportion. Think: 55 is to 100 and 5.2 is to what number? 55 h = 100 5.2Find the cross products.
520 h Divide both sides by 55. = 55 Additional Example 3A Continued When a giraffe is born, it is approximately 55% as tall as it will be as an adult. If a baby giraffe is 5.2 feet tall when it is born, how tall will it be when it is full grown, to the nearest tenth of a foot? h 9.5 Simplify. This giraffe will be approximately 9.5 feet tall when full grown.
Additional Example 3B: Life Science Application A fisherman caught a lobster that weighed 11.5 lb. This was 70% of the weight of the largest lobster that fisherman had ever caught. What was the weight, to the nearest tenth of a pound, of the largest lobster the fisherman had ever caught? Choose a method: Set up an equation. Think: 11.5 is 70% of what number? 11.5 = 70% n Set up an equation. 11.5 = 0.70 n 70% = 0.70
11.5 n = Divide both sides by 0.70. 0.70 Additional Example 3B Continued A fisherman caught a lobster that weighed 11.5 lb. This was 70% of the weight of the largest lobster that fisherman had ever caught. What was the weight, to the nearest tenth of a pound, of the largest lobster the fisherman had ever caught? 16.4 n Simplify. The largest lobster the fisherman had ever caught was about 16.4 lb.
Check It Out! Example 3A Amy caught a fish that weighed 15.5 lb. This was 85% of the weight of the largest fish that Amy had ever caught. What was the weight, to the nearest tenth of a pound, of the largest fish that Amy had ever caught? Choose a method: Set up an equation. Think: 15.5 is 85% of what number? 15.5 = 85% n Set up an equation. 15.5 = 0.85 n 85% = 0.85
15.5 n = Divide both sides by 0.85. 0.85 Check It Out! Example 3A Continued Amy caught a fish that weighed 15.5 lb. This was 85% of the weight of the largest fish that Amy had ever caught. What was the weight, to the nearest tenth of a pound, of the largest fish that Amy had ever caught? 18.2 n Simplify. The largest fish that Amy had ever caught was about 18.2 lb.
85 120 Set up a proportion. = 100 w Check It Out! Example 3B When Bart was 12, he was approximately 85% of the weight he is now. If Bart was 120 lb, how heavy is he now, to the nearest tenth of a pound? Choose a method: Set up a proportion. Think: 85 is to 100 as 120 is to what number? 85 w = 100 120 Find the cross products. 85w = 12,000 Simplify.
12000 w Divide both sides by 85. = 85 Check It Out! Example 3B Continued When Bart was 12, he was approximately 85% of the weight he is now. If Bart was 120 lb, how heavy is he now, to the nearest tenth of a pound? Simplify. w 141.2 Bart weighs approximately 141.2 lbs.
1 2 Lesson Quiz 1. 10 is 12 % of what number? 2. 326 is 25% of what number? 3. 44% of what number is 11? 4. 290% of what number is 145? 5. Larry has 9 novels about the American Revolutionary War. This represents 15% of his total book collection. How many books does Larry have in all? 80 1304 25 50 60