1. PRE-ALGEBRA

2. Using Customary Units of Measure (5-5)

3. PRE-ALGEBRA What are the customary units of measure? The customary units of measure are the units of measure we mainly use in the U.S. Using Customary Units of Measure (5-5)

4. PRE-ALGEBRA How do choose an appropriate unit of measure? To choose an appropriate unit to measure things, use units that aren’t to big (require fractions / decimals) or to small (require writing huge numbers) Using Customary Units of Measure (5-5)

5. PRE-ALGEBRA Choose an appropriate unit of measure. Explain your choice. a. weight of a hummingbird b. length of a soccer field Measure its weight in ounces, because a hummingbird is very light. Measure its length in yards, because it is too long to measure in feet or inches and too short to measure in miles. Using Customary Units of Measurement LESSON 5-5 Additional Examples

6. PRE-ALGEBRA What is a “unit analysis”? How do you use dimensional analysis to solve conversion problems in which you need to change the units in a rate? unit analysis (also called “dimensional analysis”): the process of changing units using conversion factors (unit rates in the form of fractions that include both the rate in the problem and the desired rate you want to “convert”, or change, to) To use dimensional analysis, start with the units. Multiply the given rate by conversion fractions in which the desired units cancel out so that only the desired units are left (Example: To change the numerator unit if a rate, multiply by a conversion factor in which the new units are on top and the old units are on the bottom. To change the denominator unit of a rate, multiply by a conversion factor in which new units are on the bottom and the old units are on the top ). Example: To change hours to minutes, you can multiply the number of hours by the “conversion factor” that changes the units as in: 3 hours = x = = 180 minutes Example: To change minutes to hours, you can multiply the number of hours by the “conversion fraction” as in: 300 minutes = x = 5 hours 3 hours 1 60 minutes 1 hour 180 minutes 1 300 minutes 1 1 hour 60 minutes 1 hour 60 minutes Using Customary Units of Measure (5-5)

7. PRE-ALGEBRA Use a conversion factor to convert 68 fluid ounces to cups. 68 fl oz = Use a conversion factor that changes fluid ounces to cups. 68 fl oz 1 1 c 8 fl oz 17 = Divide the common factors and units. 68 fl oz 1 c 8 fl oz 2 17 2 = c Simplify. = 8 c Write as a mixed number. 1212 There are 8 c in 68 fl oz. 1212 Using Customary Units of Measurement LESSON 5-5 Additional Examples

8. PRE-ALGEBRA Fred’s fruit stand sells homemade lemonade in 6 -pint bottles for $1.99. Jill’s fruit stand sells homemade lemonade in 3 -qt containers for the same price. At which stand do you get more lemonade for your money? 1212 1212 Since 7 pints > 6 pints, you get more lemonade for your money at Jill’s stand. 1212 3 qt = qt Use a conversion factor that changes quarts to pints 1212 7272 2 pt 1 qt = Divide the common factors and units. Use dimensional analysis to check the units. 1 2 pt 1 qt 7 qt 2 1 = 7 ptMultiply. Using Customary Units of Measurement LESSON 5-5 Additional Examples

9. PRE-ALGEBRA A wilderness group completes a 15,000-meter hike in 5.2 hours. Find the group’s rate in meters per minute. Write the rate and multiply by the conversion factor. 15,000 m 5.2 h = 15,000 m 5.2 h 1h 60 min = 15,000 m 5.2 h 1h 60 min Divide the common units. ≈ 48.1 m/min Simplify. Write the correct units. LESSON 5-5 Additional Examples Using Customary Units of Measurement

10. PRE-ALGEBRA Convert 0.7 mi to feet. There are 3,696 feet in 0.7 miles. = 3,696 ft Simplify. Because 5,280 ft = 1 mi, use the conversion factor. 5,280 ft 1 mi 0.7 mi = 0.7 mi 1 5,280 ft 1 mi Multiply by the conversion factor and divide the common units. LESSON 5-5 Additional Examples Using Customary Units of Measurement

11. PRE-ALGEBRA The fastest recorded speed for an eastern gray kangaroo is 40 mi per hour. What is the kangaroo’s speed in feet per second? The kangaroo’s speed is about 58.7 ft/s. 40 mi. 1 h 40 mi 1 h 5280 ft 1 mi 1 h 60 min LESSON 5-5 Additional Examples Use appropriate conversion factors 5280 ft 1 mi 40 mi 1 h 5280 ft 1 mi. 1 h 60 min. 1 min 60 sec = 211,200 ft 3,600 sec = 58.6 ft 1 sec   3,600 Using Customary Units of Measurement

12. PRE-ALGEBRA The director of a political campaign has a project that will take 90 volunteer-hours. The project must be completed in 6 hours. How many volunteers will the director need? 90 ÷ 6 = 15 Divide the volunteer-hours by the number of hours. The project requires 15 volunteers. volunteer hours hours = volunteers Divide the common units and simplify. The question asked for the number of volunteers, so the answer is reasonable. Check for Reasonableness Use dimensional analysis to check the units of your answer. LESSON 5-5 Additional Examples Using Customary Units of Measurement

13. PRE-ALGEBRA Choose an appropriate unit of measure. Explain your choice. 1.weight of a dog 2.length of a football field 3.Use a conversion factor to change 1 mi to ft. Pounds; dogs are too heavy to measure in ounces and too light to measure in tons. Yards; it is too long to measure in feet or inches and too short to measure in miles. 7,920 ft 1212 Lesson Quiz Using Customary Units of Measurement LESSON 5-5