Understanding Simple Probability and Odds for Algebra 1 Students

1. Algebra 1 Notes:Lesson 2-6, Part 1:Simple Probabilityand Odds

2. Objectives • Find the Probability and Odds of simple events • Describe the difference between probability and odds • Switch between probability and odds

3. Vocabulary • Probability

4. Vocabulary • Probability • Usually expressed as a fraction – CAN be a decimal or percent. • ALWAYS between 0 and 1

5. Probability The probability of an event can be expressed as: P(a) =

7. Example 1 Find the probability of rolling a number greater than 2 on a die. P(greater than 2) =

8. Example 1 Find the probability of rolling a number greater than 2 on a die. P(greater than 2) = About 67%

9. Example 2 A class contains 6 students with black hair, 8 with brown hair, 4 with blonde hair, and 2 with red hair. Find each probability. a) P(black) =

10. Example 2 A class contains 6 students with black hair, 8 with brown hair, 4 with blonde hair, and 2 with red hair. Find each probability. a) P(black) = =

11. Example 2 • A class contains 6 students with black hair, 8 with brown hair, 4 with blonde hair, and 2 with red hair. Find each probability. • P(black) = = • P(red or brown) =

12. Example 2 A class contains 6 students with black hair, 8 with brown hair, 4 with blonde hair, and 2 with red hair. Find each probability. a) P(black) = = b) P(red or brown) = =

13. Example 2 A class contains 6 students with black hair, 8 with brown hair, 4 with blonde hair, and 2 with red hair. Find each probability. a) P(black) = = b) P(red or brown) = = c) P(not blonde) =

14. Example 2 A class contains 6 students with black hair, 8 with brown hair, 4 with blonde hair, and 2 with red hair. Find each probability. a) P(black) = = b) P(red or brown) = = c) P(not blonde) = =

15. Example 2 A class contains 6 students with black hair, 8 with brown hair, 4 with blonde hair, and 2 with red hair. Find each probability. d) P(green) =

16. Example 2 A class contains 6 students with black hair, 8 with brown hair, 4 with blonde hair, and 2 with red hair. Find each probability. d) P(green) = = 0 0 20

17. Example 2 A class contains 6 students with black hair, 8 with brown hair, 4 with blonde hair, and 2 with red hair. Find each probability. d) P(green) = = 0 e) P(has hair) = 0 20

18. Example 2 A class contains 6 students with black hair, 8 with brown hair, 4 with blonde hair, and 2 with red hair. Find each probability. d) P(green) = = 0 e) P(has hair) = = 1 0 20 20 20

19. Equally Likely 0 ½ 1 impossible equally likely certain to occur to occur to occur

20. Vocabulary • Odds

21. Odds Favorable : Unfavorable

22. Example 3 Find the odds of rolling a number greater than two on a die. Numbers greater than two: 3, 4, 5, 6 Numbers not greater than two: 1, 2 Odds = 4:2

23. Example 3 Find the odds of rolling a number greater than two on a die. Numbers greater than two: 3, 4, 5, 6 Numbers not greater than two: 1, 2 Odds = 4:2 or 2:1

24. Example 4 A card is selected from a standard deck of 52 cards. What are the odds against selecting a 2 or 3? Not a 2 or 3:

26. Example 4 A card is selected from a standard deck of 52 cards. What are the odds against selecting a 2 or 3? Not a 2 or 3: 44 2 or 3:

28. Example 4 A card is selected from a standard deck of 52 cards. What are the odds against selecting a 2 or 3? Not a 2 or 3: 44 2 or 3: 8 Odds = 44:8

29. Example 4 A card is selected from a standard deck of 52 cards. What are the odds against selecting a 2 or 3? Not a 2 or 3: 44 2 or 3: 8 Odds = 44:8 or 11:2

30. Switch between probability and odds ¾ 1)

31. Switch between probability and odds ¾ 1) 3 :

32. Switch between probability and odds ¾ 1) 3 : 1 2) 5 : 3

33. Switch between probability and odds ¾ 1) 3 : 1 2) 5 : 3 ⅝

34. Homework Pgs. 99: 14-56 Evens