RATIO AND PROPORTION.powerpoint for Grade 9

Lesson ppt

1. Ratio and Proportion

2. A RATIO is a comparison by division of two numbers

3. The ratio can be written in the following form: 𝑥⁄𝑦(fraction form), x:y(read as “x is to y”),x to y

4. The word to separates the numerator and denominator quantities. The ratio of 12 to 17 translates to Numerator Denominator Unit ratio: A ratio with a denominator of 1.

5. Solve the following problems. 1. Matt and Andrew obtained 36 and 45 points, respectively , in their math quiz. Express the scores of Matt and Adrew as a ratio.

6. 2. The measures of the two consecutive angles of a parallelogram are in ratio of 5:7. Find their measure .

7. 3. An angle 40° more that its supplement. Find the ratio of the angle to its supplement.

8. Proportion is an equation in which two ratios are equal.

9. I. Determine whether each proportion is a TRUE proportion or NOT .  

14. Proportions Proportion: two ratios set equal. Cross-products of proportions are always equal! Only works if there is an equal (=) sign! No!

15. REVIEW: Supply the missing numbers or variables which will make the statement proportionality. 1.

16. 2.

17. 3.

18. Solving Proportions 1. Calculate the cross products. 2. Set the cross products equal to each other. 3. Solve the equation.

19. 1.

20. Solving Proportions 1. Calculate the cross products. 2. Set the cross products equal. 3. Solve the equation. 2.

21. Solving Proportions 1. Calculate the cross products. 2. Set the cross products equal. 3. Solve the equation. 3.

22. Find the value of the indicated variables in each proportion. 1. 10: 5 = k: 4 3. = 2. = 4.  

23. TRY! Find the value of the indicated variables in each proportion. 1. 3. 2.  

24. Set up a proportion to solve each problem . 1. The ratio of boys to girls is 3 to 2. If there are 12 boys, how many girls are there? 2. It takes one Super Giant Pizza to feed 3 people. If you invite 36 people, how many pizzas will you need?

25. 3. If two pounds of meat will serve 8 people, how many pounds will be needed to serve 1 6 people?

26. 3. If two pounds of meat will serve 8 people, how many pounds will be needed to serve 1 6 people? 4.If a jogger runs 2 miles and burns 186 calories, how many calories would he burn jogging 3 miles?

27. Jack was planting a tree. He was to dig a hole that was 3 feet deep for every 8 feet of tree height. How deep should he dig the hole for a tree that is 24 feet high?

28. A person who weighs 200 pounds on Earth would weigh about 32 pounds on the moon. Find the weight of a person on Earth who would weigh 52 pounds of the moon.

29. Because of slumping sales, a small company had to lay off some of its employees. The ratio of total employees to employees laid off is 5 to 1. Find the total number of employees if 22 are laid off.

30. FUNDAMENTAL THEOREMS OF SIMILARITY

31. Check It Out! Example 1 ∆ABC ~ ∆DEF by AA ~

32. Check It Out! Example 2 ∆ABC ~ ∆DEC by AA~