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MJ2

MJ2. Ch 7.1 - Ratios. Bellwork. Solve each equation 8 = y 3 -6 = 2 m 5 3 = 5 x 4 8. Assignment Review. Text p. 287 # 1 – 22. Before we begin…. Please take out your notebook and get ready to work….

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MJ2

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  1. MJ2 Ch 7.1 - Ratios

  2. Bellwork • Solve each equation • 8 = y 3 • -6 = 2 m 5 • 3 = 5 x 4 8

  3. Assignment Review • Text p. 287 # 1 – 22

  4. Before we begin… • Please take out your notebook and get ready to work…. • We will continue working with fractions by looking at proportional reasoning…more specifically, today we will be looking at ratios and proportions… • Raise your hand if you can tell me what a ratio is…

  5. Objective • Students will write ratios as fractions and determine if two ratios are equivalent

  6. Ratios • A ratio is a comparison of two numbers by division • There are 3 ways to write a ratio • Using the word “to” • Using a colon (:) • As a fraction • Example: 5 meters to 2 meters can be written as follows: • 5 to 2 • 5:2 • 5 2

  7. Ratios • As with fractions ratios can be expressed in simplest form Example: 25 to 10 Can be written as 25 = 5 10 2

  8. Your Turn • In the notes section of your notebook write each ratio and express it as a fraction in simplest form • 9 to 12 • 27 to 15 • 8:56

  9. Ratios with different measures • Sometimes you will be given a ratio with different unit values and asked to write it as a ratio in simplest form • BE CAREFUL HERE! – when writing ratios comparing units of length, time, weight, etc… both measures should be in the same unit… • Students often make a mistake here! • Let’s look at an example…

  10. Example • Write a ratio of 2 feet to 10 inches as a fraction in simplest form. Set up the ratio 2 feet 10 inches Convert the feet to inches 24 inches 10 inches Simplify 12 5

  11. Your Turn • In the notes section of your notebook write the ratios then convert them to a fraction in simplest form. • 4 feet: 4 yards • 15 ounces to 3 pounds • 9 hours to 3 days

  12. Comparing Ratios • Sometimes you will be asked to compare ratios to determine if they are equivalent (equal) to each other • To do so write each ratio as a fraction equal to each other and then cross multiply. • If both sides equal then the ratios are equivalent • Let’s look at an example…

  13. Example • Determine if 6:8 and 36:48 are equivalent Set up the fractions 6 = 36 8 48 Cross multiply 288 = 288 Since 288 is equal to 288 the ratios are equivalent. IMPORTANT! – you can only cross-multiply if there is an equal sign between 2 ratios

  14. Non-Example • Determine if 9:2 and 45:6 are equivalent Set up the fractions 9 = 45 2 6 Cross Multiply 90 ≠ 54 In this instance 90 does not equal 54 so the ratios are not equivalent

  15. Your Turn • In the notes section of your notebook write each ratio and determine if they are equivalent. • 3 and 6 8 12 • 35 students to 5 adults and 14 students to 2 adults

  16. Summary • In the notes section of your notebook summarize the key concepts covered in today’s lesson • Today we discussed • Ratios – what are they? • How do you write a ratio? • How can you tell if ratios are equivalent?

  17. Assignment • Text p. 290 # 14 – 29 • Write the problem and your answer • I do not accept answers only! • This assignment is due tomorrow

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