H on using estimation

Transcription

1 H on using estimation

2 To the Student In FOCUS on Using Estimation, Book H, you will read problems and answer questions. You will practice using a math strategy called Using Estimation. You will learn about the strategy on the Learn About pages. You will see a sample passage, sample questions, and sample answer choices on the Lesson Preview pages. Then you will practice using the strategy in twenty lessons. Each lesson has a passage and five questions. After you finish reading the passage, answer the five questions. For the first four questions, fill in the correct answers on the Answer Form on page 53. Or, you may fill in the correct answers directly on the page. For the fifth question, show your work. Then write and explain your answer. Fill in the circle on the Answer Form to show that you have completed the fifth question. Use the Tracking Chart on page 47 to show when you have finished each lesson and the number of questions that you answered correctly. After each group of five lessons, complete a self-assessment to see how you are doing. So... FOCUS and enjoy! Acknowledgments Product Development Project Developer: Mazer Creative Services Curriculum Associates Project Editor: Pamela Halloran Curriculum Associates Project Designer: Susan Hawk Photo and Illustration Credits Pgs. 8, 10, 12, 20, 36, 40, 44, 2008 JupiterImages Corporation Shutterstock.com: cover Yan Vugenfirer, pg. 6 Seleznev Anton Aleksandrovich, pg. 14 Carolyn M Carpenter, pg. 16 Zorylee Diaz-Lupitou, pg. 18 Eric Lsselee, pg. 22 John Leung, pg. 24 Sebastian Kaulitzki, pg. 26 Losevsky Pavel, pg. 28 Lon Martin, pg. 30 Stockbroker, pg. 32 Stephen Coburn, pg. 34 Lopalinsky Viadislav, pg. 38 Eric Limon, pg. 42 Gina Smith ISBN Curriculum Associates, Inc. North Billerica, MA No part of this book may be reproduced by any means without written permission from the publisher. All Rights Reserved. Printed in USA

3 Table of Contents Learn About... 2 Lesson Preview... 4 Lesson 1 Area of Earth s Surface... 6 Lesson 2 Radio Channels... 8 Lesson 3 Water, Water Everywhere Lesson 4 Stars and Colors Lesson 5 The National Library Lesson 6 Populations Near Segoville Lesson 7 Feeding the Elephants Lesson 8 Too Many Sodas! Lesson 9 Amusement Park Lesson 10 Around the Sun Lesson 11 Small-Town Movie Theater Lesson 12 Spring Carnival Lesson 13 Increasing Student Population Lesson 14 Bakery Specials Lesson 15 Auto Rentals Lesson 16 Treadmills Lesson 17 Rain Studies Lesson 18 Business Travel Lesson 19 Handcrafted Items Lesson 20 Family Vacations Tracking Chart Self-Assessment 1, Lessons Self-Assessment 2, Lessons Self-Assessment 3, Lessons Self-Assessment 4, Lessons Self-Assessment 5, Lessons Answer Form... 53

4 Learn About Using Estimation: Rounding Numbers An estimate is a number that is close to the actual number you are looking for. Numbers can be rounded to the nearest ten, hundred, thousand, ten thousand, and so forth. Decimals can be rounded to the nearest whole number, tenth, hundredth, thousandth, and so forth. If the digit one place to the right of the place being rounded to is 5 or greater, round up. If the digit one place to the right of the place being rounded to is 4 or less, round down. For example, the number , when rounded to the nearest tenth, is because the hundredths place contains the digit 6, which is greater than 5. You can also round mixed numbers. When rounding mixed numbers round to the nearest whole number: round up if the fraction is 1 or more; 2 round down if the fraction is less than 1 2. For example, 23 5 rounds up to 24 8 because 5 8 is greater than 1 2. Kaitlyn is building a trundle wheel to measure distances. She calculated the circumference of the wheel as inches. Her teacher asked the students to round their circumferences to the nearest hundredth. What is the circumference of Kaitlyn s trundle wheel, rounded to the nearest hundredth? The digit in the thousandths place is 5, so round up. The rounded circumference is inches. Remember: Numbers can be rounded to the nearest ten, hundred, thousand, ten thousand, and so forth. Decimals can be rounded to the nearest whole number, tenth, hundredth, thousandth, and so forth. The number 5 is the midpoint for rounding. 2

5 Learn About Using Estimation: Estimating Sums, Differences, Products, and Quotients Sums, differences, products, and quotients can be estimated. Before performing the calculations, round the numbers. Use numbers that are easy to work with, such as multiples of ten. A quotient is estimated by rounding the dividend and/or the divisor to numbers that are easy to work with. Equation To the Nearest Estimate Sum 64, ,842 = x thousand 64, ,000 = 80,000 Difference = x hundred = 200 Product = x ten/whole number 20 5 = 100 Kirsten collects payments for the community newspaper. Each customer pays $1.75 for a subscription. Today, Kirsten collected payments from 28 customers. Rounding to the nearest dollar and the nearest ten customers, about how much money did Kirsten collect today? Round $1.75 to the nearest dollar: $1.75 rounds to $2. Round 28 to the nearest ten: 28 rounds to 30. $2 30 = $60 Kirsten collected about $60 today. Remember: Sums, differences, products, and quotients can be estimated. Before performing the calculations, round the numbers. Use numbers that are easy to work with, such as multiples of ten. A quotient is estimated by rounding the dividend and/or the divisor to numbers that are easy to work with. 3

6 Lesson 20 Read the passage. Then do Numbers 1 5. Family Vacations The Solomon family takes at least two family vacations each year. They also take short weekend trips together. They usually travel by car because they enjoy seeing the sights while traveling. Mr. and Mrs. Solomon set the trip meter in the car when they embark on a new trip. They keep track of how many miles they drive while on vacation. 1. The Solomons drove a total of 982 miles during their first vacation this year. What is this distance rounded to the nearest hundred miles? A 900 mi B 980 mi C 990 mi D 1,000 mi 2. The Solomons traveled a total of 426 miles during their first weekend trip. They traveled half of this distance during their second weekend trip. Round the distance of their first weekend trip to the nearest ten miles. Approximately how many miles did they travel during their second weekend trip? A about 200 miles B about 210 miles C about 215 miles D about 250 miles 44

7 3. In July, the Solomons took a 7-day vacation and drove 1,108 miles. What is this distance rounded to the nearest hundred miles? A 1,000 mi B 1,100 mi C 1,110 mi D 1,200 mi 4. The Solomons went on a 4-day trip before the school year started. They drove a total of 538 miles on this trip. Mrs. Solomon rounded the total distance to the nearest ten miles and correctly estimated the average distance traveled each day. What was her estimate? A about 125 miles B about 130 miles C about 135 miles D about 150 miles 5. At the end of each year, Mr. Solomon adds up the number of miles that the family drove on all of their family trips during the year. They drove a total of 4,223 miles on all of their trips last year. They drove a total of 3,584 miles on all of their trips this year. Round both distances to the nearest hundred miles. What is the estimated ratio of the number of vacation miles this year to the number of vacation miles last year? Show your work in the space below. Remember to check your solution. Write your solution. Explain how you found your solution. 45