Chapter 3 – Solving Linear Equations 3.8 – Rates, Ratios, and Percents

Today we will learn how to: Today we will learn how to: Use rates and ratios to model and solve real- life problems Use rates and ratios to model and solve real- life problems Use percents to model and solve real-life problems Use percents to model and solve real-life problems

3.8 – Rates, Ratios, and Percents If you have two quantities with different units, the RATE OF A per B is a/b. If you have two quantities with different units, the RATE OF A per B is a/b. Rates are commonly expressed as unit rates. Rates are commonly expressed as unit rates. A UNIT RATE is a rate per one unit. A UNIT RATE is a rate per one unit.

3.8 – Rates, Ratios, and Percents Example 1 Example 1 Estimated spending in U.S. in 1996 Estimated spending in U.S. in 1996 Find the cost per person, assuming the U.S. population in 1996 was about 266 million. Find the cost per person, assuming the U.S. population in 1996 was about 266 million. Medical Care $913 billion Housing $787 billion Transportation $602 billion

3.8 – Rates, Ratios, and Percents Example 2 Example 2 You have recorded your car mileage and gasoline use for 5 weeks. Estimate the number of miles you can drive on a full 12- gallon tank of gasoline. You have recorded your car mileage and gasoline use for 5 weeks. Estimate the number of miles you can drive on a full 12- gallon tank of gasoline. Number of miles Number of gallons

3.8 – Rates, Ratios, and Percents Example 3 Example 3 You are visiting Canada and you want to exchange $150 for Canadian dollars. The rate of currency exchange is 1.4 Canadian dollars per United States. You want to find how many Canadian dollars you will receive. You are visiting Canada and you want to exchange $150 for Canadian dollars. The rate of currency exchange is 1.4 Canadian dollars per United States. You want to find how many Canadian dollars you will receive. When you leave Canada you find that you have 15 Canadian dollars left. You want to find how much you can get in United States dollars. The rate of currency exchange is now 1.3 Canadian dollars per U.S. dollar. When you leave Canada you find that you have 15 Canadian dollars left. You want to find how much you can get in United States dollars. The rate of currency exchange is now 1.3 Canadian dollars per U.S. dollar.

3.8 – Rates, Ratios, and Percents Example 4 Example 4 You tested a sample of 100 packages from a shipment of 6000 packages. You found that 70 packages were under weight. Estimate the number of packages that will be under weight. You tested a sample of 100 packages from a shipment of 6000 packages. You found that 70 packages were under weight. Estimate the number of packages that will be under weight.

3.8 – Rates, Ratios, and Percents Example 5 Example 5 About 74% of water used in houses is used in bathrooms, about 5% in kitchens, and about 21% in other places. About 9 gallons are used in the kitchen each day. Estimate the total gallons used each day. About 74% of water used in houses is used in bathrooms, about 5% in kitchens, and about 21% in other places. About 9 gallons are used in the kitchen each day. Estimate the total gallons used each day.

3.8 – Rates, Ratios, and Percents CLASSWORK 3.8 Practice A Worksheet

3.8 – Rates, Ratios, and Percents HOMEWORK Page 183 #11 – 18, 23 – 29, 33 – 35