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Warm Up. Simplify each product. Chapter 4 Solving & Applying Proportions. Section 4 – 1 Ratio & Proportion. Objectives: To find ratios & proportions To solve proportions. Ratio :. A comparison of two numbers by division. The ratio of a to b is: a : b or , where b ≠ 0. Examples:
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Warm Up Simplify each product.
Section 4 – 1 Ratio & Proportion Objectives: To find ratios & proportions To solve proportions
Ratio: A comparison of two numbers by division The ratio of a to b is: a : b or , where b ≠ 0 Examples: Ratio of Girls to Boys is : 10 : 9 The Ratio of the number of Miles Run in 20 Minutes is :
Rate: When a and b represent quantities measured in different units Unit Rate: A rate with a denominator of 1. Example:
Example 1 Using Unit Rates The table at the right gives prices for different sizes of Gatorade. A) Find the unit rate for the 12-oz size.
B) Find the unit rates for the other two sizes. C) Which of the three sizes has the lowest cost per ounce? D) Why are unit rates important?
Unit Analysis: The process of selecting conversion factors to produce the appropriate factors. Example: You need to convert 3 hours to minutes. Conversion factor: To change hours to minutes, multiply by the conversion factor: = 180 Minutes
Example: You need to convert 9 feet to yards. Conversion factor: To change feet to yards, multiply by the conversion factor: = 3 yards
Example: You need to convert 300 feet to miles. Conversion factor: To change feet to miles, multiply by the conversion factor: ≈ .06 miles
Important Conversions: 16 ounces = 1 pound 100 cm= 1 meter 12 inches = 1 feet 3 feet = 1 yard 5,280 feet = 1 mile 60 seconds = 1 minute 60 minutes = 1 hour 24 hours = 1 day 365 days = 1 year
Example 2 Converting Rates A) A cheetah ran 300 feet in 2.92 seconds. What was the cheetah’s speed in miles per hour?
Homework Textbook Page 185 – 186; #1 – 13, 38 – 42 Even
B) A sloth travels 0.15 miles per hour. Convert this speed to feet per minute.
Section 4 – 1 Continued Objectives: To solve proportions
Proportion: An equation that states that two ratios are equal Example:
Cross Products: In the proportion, : ad and bc are the cross products Cross Products of a Proportion: If , then ad = bc Example: , so 2(12) = 3(8)
Example 4 Using Cross Products • Use cross products to solve the proportion • Use cross products to solve the proportion
Use cross products to solve the proportion • Use cross products to solve the proportion
Example 5 Solving Multi-Step Proportions A) Solve the proportion
Solve • Solve
D) Solve E) Solve
You can use proportions to solve world problems! To write a correct proportion, form rates on each side that compare units in the same way, Example:
Example 6 Real-World P.S. A) In 2001, Lance Armstrong won the Tour de France, completing the 3454 – km course in about 86.3 hours. Traveling at his average speed, how long would it take him to ride 185 km? Round your answer to the nearest tenth.
Suppose you walk 2 miles in 35 minutes. How far would you walk in 60 minutes, if you were to continue at the same rate? • Suppose you walk 5 miles in 45 minutes. How far would you walk in 1 hour, if you were to continue at the same rate?
Homework Page 185 – 186; #14 – 28 Even & 32 - 37