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In this pdf, we will learn how to compare and order fractions. A fraction represents a part of a whole or, more generally, any number of equal parts. When spoken in everyday English, a fraction describes how many parts of a certain size there are, for example, one-half, eight-fifths, three-quarters.
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12-NEM6 WBAns 8/8/05 3:07 PM Page 104 CHAPTER 12 1 Comparing and Ordering Fractions Goal Compare and order fractions on number lines. 1. Compare. Write >, <, or . At-Home Help 1 To compare fractions, use a 0 1 11 2 21 3 2 2 2 number line to mark the positions of the fractions. The order of the fractions can be read from the number line. 4 a) > 2 d) 1 1 < 1 4 For example, to order 34, 38, 3 3 3 6 and 23, use a number line. 2 4 3 1 b) = e) 1 < 2 3 2 3 5 10 4 2 8 3 4 7 3 1 1 0 1 c) > f) 2 > 2 4 8 5 10 2. Order each set of numbers from least to greatest. The order from least to greatest is 38, 23, and 34. Use a number line. 3 1 3 5 a) , 1, , 8 4 4 8 3 5 3 11 0 1 2 3 5 3 1 8 8 4 4 , , , 1 8 8 4 4 1 2 8 3 b) 2, 1, , 1 3 3 3 6 13 12 21 8 3 2 1 8 1 6 3 2 3 3 3 1, 1, 2, 6 3 3 3 4 1 2 7 5 c) , 1, , , 1 4 8 4 4 8 2 11 15 7 0 1 8 2 2 4 1 5 7 4 8 4 , , 1, 1, 4 4 8 8 4 4 4 5 2 1 1 6 d) , , , 1, 6 3 6 3 3 1 2 5 11 0 1 2 1 2 5 1 6 6 3 6 3 , , , 1 , 6 3 6 3 3 6 3 104 Answers Chapter 12: Fractions, Decimals, Ratios, and Percents Copyright © 2006 Nelson
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12-NEM6 WBAns 8/8/05 3:07 PM Page 105 CHAPTER 12 Comparing Fractions with 2 Unlike Denominators Goal Compare fractions when the denominators are different. 1. Compare. Write >, <, or . At-Home Help 1 4 3 2 To compare fractions with unlike a) < d) > 3 5 4 3 denominators, draw a number line 2 1 6 on grid paper. b) < e) = 3 5 2 10 5 Choose a whole that you can easily 3 1 1 c) > f) 1 > 5 divide by each denominator. 8 3 2 8 For example, to compare 34, 23, 2. Which amount is greater? Tell how you know. and 32, choose a whole with 1 3 12 sections. a) or of a bag of popcorn 3 8 Then mark the fractions on the 3 number line. 8 2 3 Suggested answer: 3 2 I used grid paper to draw a number line. I chose 0 1 2 a whole with 24 sections. 3 1 is past 3 on the number line. 3 8 4 2 2 b) or of a container of juice The order from least to greatest 5 3 is 23, 34, and 32. 2 3 Suggested answer: The numerators are the same, so the fraction with the lower denominator is greater. 5 1 c) or of a length of string 7 2 5 7 Suggested answer: I used grid paper to draw a number line. I chose a whole with 14 sections. 5 1 is past on the number line. 7 2 Copyright © 2006 Nelson Answers Chapter 12: Fractions, Decimals, Ratios, and Percents 105
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12-NEM6 WBAns 8/8/05 3:07 PM Page 106 CHAPTER 12 3 Fraction and Decimal Equivalents Goal Relate fractions to decimals and determine equivalents. 1. Write an equivalent fraction for each decimal. At-Home Help 34 To write a fraction as a decimal, a) 0.34 100 find an equivalent fraction with a denominator of 10, 100, or 1000. 6 Then use place value to write the b) 0.6 10 decimal equivalent. 7 For example: c) 0.07 100 2 4 5 10 3 1 4 tenths d) 1.3 10 0.4 37 To write a decimal as a fraction, 2 e) 2.37 100 use place value. 4 For example: 3 f) 3.04 100 2.1 2 ones 1 tenth 1 2 10 4 2. Explain how to write as a decimal. 5 Suggested answer: I could divide a rectangle into 10 equal sections. 4 If I shade 4 rows, that represents . 5 4 of the rectangle is 8 sections. 5 4 So is the same as 0.8. 5 106 Answers Chapter 12: Fractions, Decimals, Ratios, and Percents Copyright © 2006 Nelson
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12-NEM6 WBAns 8/8/05 3:07 PM Page 107 CHAPTER 12 4 Ratios Goal Identify and model ratios to describe situations. 1. Write the ratio of grey items to white items. At-Home Help a) 5 : 6 A ratio is a comparison of two numbers or quantities measured in the same units. If you mix juice using 1 can of concentrate and 3 cans of water, the ratio of concentrate to water is 1 : 3, or 1 to 3. b) 2 : 5 c) 8 : 3 d) 0 : 6 2. Write the ratio of white to grey for each situation in Question 1. a) 6 : 5 b) 5 : 2 c) 3 : 8 d) 6 : 0 3. a) What is the ratio of oats to raisins? 3:2 3 parts oats b) What is the ratio of coconut to oats? 1 part coconut 1:3 2 parts raisins c) What is the ratio of raisins to coconut? 2:1 Copyright © 2006 Nelson Answers Chapter 12: Fractions, Decimals, Ratios, and Percents 107
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12-NEM6 WBAns 8/8/05 3:07 PM Page 108 CHAPTER 12 5 Equivalent Ratios Goal Determine equivalent ratios and use them to solve problems. 1. Determine the missing number to make an At-Home Help equivalent ratio. Equivalent ratios are two or more ratios that represent the a) 5 to 8 10 to 16 same comparison. b) 12 : 100 3 : 25 1:3 2:6 3:9 c) 21 to 33 7 to 11 d) 18 : 6 9 :3 e) 75 : 24 25 : 8 f) 24 to 60 2 to 5 2. Kenton makes salsa by mixing tomatoes and peppers in a ratio of 5 to 2. a) Write ratios equivalent to 5 : 2 in the ratio table. Tomatoes 5 10 15 20 25 30 Peppers 2 4 6 8 10 12 b) If Kenton has 40 tomatoes, how many peppers does he need? 5 : 2 = 40 : 16 16 peppers c) If Kenton has 20 peppers, how many tomatoes does he need? 5 : 2 = 50 : 20 50 tomatoes 3. Stacy makes one batch of muffins using muffin mix and water in a ratio of 3 : 1. She needs to make 4 batches for school. How many cups of muffin mix will she need? 3 : 1 = 12 : 4 12 cups of muffin mix 108 Answers Chapter 12: Fractions, Decimals, Ratios, and Percents Copyright © 2006 Nelson
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12-NEM6 WBAns 8/8/05 3:07 PM Page 109 CHAPTER 12 6 Percents as Special Ratios Goal Understand the meaning of percent. 1. Write each as a ratio, a fraction, and a percent. At-Home Help a) 10 to 25 c) 13 out of 20 A percent is a part-to-whole ratio that compares a number or an 10 : 25 13 : 20 amount to 100. 10 40 13 65 = = 25 100 20 100 25% 25 : 100 = 40% = 65% 25 100 b) 0.07 d) 0.18 Percents are written with a percent sign (%). The percent sign is like 7 : 100 18 : 100 writing “of each 100.” 25% is read 7 18 = 7% = 18% “25 percent” and means “25 of 100 100 each 100.” 2. Write each ratio as an equivalent fraction with 100% means the whole. a denominator of 100, a decimal, and a percent. 9 33 a) = 45 b) = 66 c) 2 out of 5 d) 8 out of 25 20 100 50 100 = 0.45 = 0.66 2 40 8 32 = = = 45% = 66% 5 100 25 100 = 0.40 = 0.32 = 40% = 32% 3. A survey at Jennifer’s school showed that 19 out of 25 students chose pizza as their favourite lunch food. a) What percent of students chose pizza? 19 out of 25 = 19 : 25 19 = 25 76 = 100 = 76% b) What percent of students did not choose pizza? Suggested answer: Out of 25 students, 25 – 19 = 6 students did not choose pizza. 6 out of 25 = 6 : 25 6 = 25 24 = 100 = 24% Copyright © 2006 Nelson Answers Chapter 12: Fractions, Decimals, Ratios, and Percents 109
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12-NEM6 WBAns 8/8/05 3:07 PM Page 110 CHAPTER 12 7 Relating Percents to Decimals and Fractions Goal Compare and order percents, fractions, and decimals. 1. Write each number as a percent. Order the At-Home Help numbers from least to greatest. To compare fractions, decimals, 7 8 and percents, write all numbers a) 0.6, , 0.07, 10 20 in the same form. 6 7 70 7 8 40 1 0.6 = = 0.07 = = For example, to compare , 0.11, 4 10 10 100 100 20 100 1 , and 30%, write each number as 60 = 70% = 7% = 40% 5 = a percent. 100 = 60% 1 25 11 1 20 0.11 4 100 100 5 100 8 7 25% 11% 20% Order is 7%, 40%, 60%, 70% or 0.07, , 0.6, . 20 10 The order from least to greatest is 4 16 11%, 20%, 25%, 30% or b) , 0.12, , 0.85 5 25 1 1 0.11, , , 30%. 5 4 4 80 12 16 64 85 = 0.12 = = 0.85 = 5 100 100 25 100 100 = 80% = 12% = 64% = 85% 16 4 Order is 12%, 64%, 80%, 85% or 0.12, , , 0.85. 25 5 2. An art show has paintings, sculptures, and sketches. Thirty-five percent of the items are paintings and 0.13 of the items are sketches. What fraction of the items are sculptures? Suggested answer: 35% paintings 13 0.13 = 100 = 13% sketches Percent of sculptures = 100% – (35% + 13%) = 100% – 48% = 52% 52 52% = 100 13 = 25 13 The fraction of items that are sculptures is . 25 110 Answers Chapter 12: Fractions, Decimals, Ratios, and Percents Copyright © 2006 Nelson
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12-NEM6 WBAns 8/8/05 3:07 PM Page 111 CHAPTER 12 8 Estimating and Calculating Percents Goal Estimate and calculate percents. 1. Estimate the percent of each number. At-Home Help Show your work. To estimate the percent of a number, use benchmarks such a) 40% of 180 as 10%, 25%, 50%, and 75%. Suggested answer: 1 10% is the same as . 50% of 180 is half of 180, or 90. 10 1 So 40% of 180 is a little less than 90 or about 75. 25% is the same as . 4 1 50% is the same as . 2 3 b) 30% of 90 75% is the same as . 4 Suggested answer: 100% is the same as 1 whole. 10% of 90 is 9. For example, to estimate 25% of 30% of 90 is 9 x 3 = 27. 500 km, use a number line. 0% 25% 50% 75% 100% c) 50% of 412 0 about 250 500 100 Suggested answer: 50% of 500 km is half of 500 50% of 412 is half of 412, or about 200. or 250 km. So 25% is half of 250 km or about 100 km. d) 75% of 208 Suggested answer: 50% of 208 is half of 208, or about 100. 25% of 208 is about half of 100, or 50. So 75% of 208 is about 100 + 50 = 150. 2. A store has a sign saying, “15% off all jackets.” Kenny wants to buy a leather jacket that has a regular price of $360. About how much will Kenny save? Suggested answer: 1 25% of $360 is of $360, or $90. 4 15% is about halfway between 0 and 25% but closer to 25%. So 15% of $360 is about half of 90, or about $50. So Kenny will save about $50. Copyright © 2006 Nelson Answers Chapter 12: Fractions, Decimals, Ratios, and Percents 111
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12-NEM6 WBAns 8/8/05 3:07 PM Page 112 CHAPTER 12 9 Unit Rates Goal Represent relationships using unit rates. 1. Calculate the unit rate for each item. At-Home Help a) 5 guitar picks for $1.00 A unit rate is a comparison of two quantities where the second one is Suggested answer: 20¢/pick described as one unit. For example, a unit rate might be 30 km in 1 h or 4 tomatoes for $1.00. Rates often have words like “per” or “for” in them. A slash (/) is b) 2 CDs for $15.00 sometimes used instead. Suggested answer: For example, you read 100 km/h 2 : 15 = 1 : as “100 km per hour.” = 7.5 $7.50/CD c) 8 mini-muffins for $2.40 d) 3 tickets for $3.00 Suggested answer: 30¢/muffin Suggested answer: 3:3=1: =1 $1.00/ticket 2. a) What is the price of one scoop of each type of ice cream? Ice cream Suggested answer: Vanilla (vanilla) 3 : 150¢ = 1 : (mango) 4 : 4 = 1 : 3 scoops for $1.50 = 50 =1 Chocolate 50¢/scoop $1.00/scoop 2 scoops for $1.40 Mango (chocolate) 2 : 140¢ = 1 : (strawberry) 4 : 360¢ = 1 : 4 scoops for $4.00 = 70 = 90 Strawberry 70¢/scoop 90¢/scoop 4 scoops for $3.60 b) Which ice cream is the least expensive? vanilla c) Which ice cream is the most expensive? mango 112 Answers Chapter 12: Fractions, Decimals, Ratios, and Percents Copyright © 2006 Nelson
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12-NEM6 WBAns 8/8/05 3:07 PM Page 113 CHAPTER 12 10 Solving Problems Using Guess and Test Goal Use a guess and test strategy to solve problems. The ratio of flowers to herbs in Babak’s garden is 6 : 2. At-Home Help He started with 80 plants. He wants to increase the Sometimes using a guess and number of herbs in his garden so that 40% of his plants test strategy is a good way to are herbs. How many more herb plants must he get? solve a problem. Suggested answer: Use a chart to help you organize the information you are given and Understand the Problem what you want to calculate. Babak started with 80 plants that made 100% of his garden. Remember to check if your answer If Babak had 8 plants, 6 of them would be flowers and 2 is reasonable after guessing. would be herbs. 0% 25% 50% 75% 100% 0 20 40 60 80 Make a Plan I’ll set up a chart and use a guess and test strategy to determine how many more herb plants Babak needs. Carry Out the Plan Number Number Total number of Guess of flowers of herbs flowers and herbs Percent of herbs 20 1 start with 60 20 80 = = 25% 80 4 30 1 add 10 herbs 60 30 90 = 90 3 or about 30% 40 add 20 herbs 60 40 100 = 40% 100 Look Back Babak will need 20 more herb plants to make his garden have 40% herbs. I’ll check if my answer is correct. Babak started with 80 plants. If he adds 20 plants, then he will have 80 + 20 = 100 plants altogether. 40% of 100 is 40. So he should have 60 flowers and 40 herbs. He started out with 20 herbs. So 20 more herb plants will give 40 herb plants. Copyright © 2006 Nelson Answers Chapter 12: Fractions, Decimals, Ratios, and Percents 113
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12-NEM6 WBAns 8/8/05 3:07 PM Page 114 CHAPTER 12 Test Yourself Page 1 Circle the correct answer. 1. Which fraction is greatest? 4 2 3 3 , , , 5 3 4 8 4 2 3 3 A. B. C. D. 5 3 4 8 2. What is the correct order of these fractions from least to greatest? 2 1 1 7 2 , , 1, , 3 6 5 8 5 2 2 1 7 1 1 2 2 7 1 A. , , , , 1 C. , , , , 1 5 3 6 8 5 6 3 5 8 5 1 2 2 7 1 2 2 1 7 1 B. , , , , 1 D. , , , , 1 6 5 3 8 5 3 5 6 8 5 3. What is 1.03 as a fraction? 13 3 3 103 A. B. 1 C. 1 D. 100 10 100 1000 4. What is the ratio of white counters to grey counters? A. 4 : 3 C. 4 : 7 B. 3 : 7 D. 3 : 4 5. Which ratios are equivalent to 6 out of 15? i) 2 : 5 ii) 3 out of 10 iii) 4 out of 10 iv) 10 : 25 v) 20 : 45 A. i, ii, iii B. ii, iv, v C. i, iii, iv D. ii, iii, iv 6. What is the correct order of these numbers from least to greatest? 8 2 , 0.14, 30%, , 8%, 0.09 25 5 8 2 2 8 A. 8%, 0.09, 0.14, 30%, , C. 0.09, , 0.14, , 8%, 30% 25 5 5 25 2 8 2 8 B. 0.09, 0.14, , , 8%, 30% D. 8%, 0.09, , 0.14, , 30% 5 25 5 25 114 Answers Chapter 12: Fractions, Decimals, Ratios, and Percents Copyright © 2006 Nelson
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12-NEM6 WBAns 8/8/05 3:07 PM Page 115 CHAPTER 12 Test Yourself Page 2 7. What is 0.3 as a ratio, a fraction, and a percent? 3 A. 3 : 100, , 30% 100 3 B. 3 : 10, , 30% 10 3 C. 3 : 10, , 3% 10 3 D. 3 : 10, , 3% 100 12 8. What is as an equivalent fraction with a denominator of 100, a decimal, 25 and a percent? 12 A. , 0.12, 12% 100 40 B. , 0.4, 40% 100 48 C. , 0.48, 48% 100 16 D. , 0.16, 16% 100 9. What is the best estimate for 25% of 212? A. about 30 B. about 40 C. about 50 D. about 60 10. Which type of muffin is the least expensive? Muffins A. cinnamon raisin Blueberry bran . . . . . 5 for $3.50 B. maple pecan Cranberry orange . . . 6 for $3.60 Crunchy oat . . . . . . . 8 for $3.20 C. cranberry orange Maple pecan . . . . . . 3 for $2.70 D. crunchy oat Cinnamon raisin . . . . 5 for $2.50 11. A brand of light cheese says “20% less fat” on the label. The regular version of the cheese has 85 g of fat. About how many fewer grams of fat are in the light cheese? A. about 10 g B. about 20 g C. about 30 g D. about 40 g Copyright © 2006 Nelson Answers Chapter 12:Fractions, Decimals, Ratios, and Percents 115