1. Probability

2. Example: A six sided die – 1, 2, 3, 4, 5, 6
Probability – a ratio that tells how likely it is that an event will take place.
probability =
Example: A six sided die – 1, 2, 3, 4, 5, 6
What is the probability of getting a 2
or P(2)?
1. P(odd number) =
2. P(a number less than 1) =
3. P(a number less than 3) =

3. Another example:
I’ve got 13 CD’s. 6 are rock CD’s, 3 are country CD’s, and 4 are movie sound track CD’s. If I choose a CD at random, what is the probability that I will choose a country CD?
P(Country CD) =
P(A movie sound track CD) =

4. Independent events – two or more events in which the outcome of one event does not affect the outcome of the other.
Example: I have a coin and a spinner:
RED Blue
Green Green
1. What is P(heads and blue) =
2. P(heads and green) =

5. Another example of independent events:
On a six-sided die:
1. P(2 and 3) =
2. P(3, 4, and 5) =

6. Now you try: You have a six-sided die and a spinner
1. P(5 and orange) =
2. P(even number and yellow) =
3. P(3 and black) =

7. Dependent Events: two or more events in which the outcome of one event does affect the outcome of the other event.
Can you think of an example?
Example: You are going to draw a card out of a deck of cards. The first one is not replaced.
1. What is P(a king and then a 3) =
2. P(a queen and then a heart) =

8. Another example of dependent events:
In a bag there are 5 red marbles, 2 green marbles, 4 yellow marbles, and 3 blue marbles. Once a marble is drawn, it is not replaced. Find:
1. P(green and then green) =
2. P(red, green, and then a blue) =

9. Now you try:
Find the probability of drawing each of the following letters in MATHEMATICAL if the letters are not replaced:
P(A and then T) =
2. P(a vowel and then a vowel) =

10. Independent or Dependent?
1. Rolling a die twice?
2. Selecting a name from the Greenville phone book and a name from the Greer phone book?
3. As team captain, selecting someone to be on your basketball team and then selecting a second player?
4. Tossing a coin and spinning a spinner?
5. Choosing a card from a deck of cards and then choosing a second card without replacing the first card?

11. TOD:
1. Explain the difference between independent and dependent events.
2. Pick one of the following:
Write an example of two independent events.
Write an example of two dependent events
3. What math operation does the word and represent in this statement:
P(drawing a king and then a queen)

12. The chart below lists the number and type of two soft drinks found in a tub filled with ice. Two cans are selected at random. Find the probability of the following:
Soda
Regular
Diet
Orange 3 4
Lemon-lime 7 6
1. a diet orange and a regular lemon-lime
2. a regular orange and a regular lemon-lime
3. A diet lemon-lime and a regular lemon-lime
4. a regular orange and a diet lemon-lime.

13. Odds (in favor) – the ratio of the number of ways the outcome can occur (successes) to the number of ways the outcome cannot occur (failures).
odds (in favor) = # of successes : # of failures
Example: A bag contains 5 green marbles, 2 yellow marbles, and 3 blue marbles.
What are the odds of drawing a green marble from the bag?
Yellow?

14. Another example
Find the odds in favor of each outcome if a die is rolled:
A number greater than 5
A number less than 4
A multiple of 2 or a 1
Not a 3

15. Now you try:
Example: The door prize at a party with 25 people is given by writing numbers 1 through 25 on the bottom of the paper plates used.
What is the probability that an individual had the winning plate?
2. What are the odds of winning a door prize?
3. What are the odds of not winning a door prize?

16. Odds (against) – the ratio of the numbers of ways the outcome cannot occur (failures) to the number of ways the outcome can occur (successes).
odds (against) = # of failures : # of successes
**What do you notice about odds in favor and odds against?
Let’s look at previous examples

17. Example: A card is selected at random from a deck of 52 cards.
What are the odds against selecting a heart or what are the odds of not selecting a heart?
What are the odds against selecting an ace or what are the odds of not selecting an ace?

18. Now you try:
You have a bag full of M&Ms. There are 12 red, 10 blue, 8 green, 6 yellow, and 4 orange.
What are the odds of you not randomly pulling out an orange M&M?
2. Not a blue nor a red M&M?

19. Consider this example:
1. The odds of an event are 2:5. What is the probability of the same event?
2. The odds of an event are 3:7. What is the probability of the same event?

20. Red Workbook p. 87 (2-22 evens)
Homework
Red Workbook p. 87 (2-22 evens)

21. Example: The spinner below is spun.
P(yellow or 2) =
2. P(red or 5) =
3. P(3 or blue) = 1 6 2 5 3 4