Probability

1. Probability

2. Probability of an Event…..

3. Example….. • What is the probability of rolling a “3” on a six sided die? • Answer…… • There is one “3” on a die and there are six sides.

4. Example…… • Use the figure to the right. Suppose you throw a dart without looking where it lands on the dart board. • What is the probability that it will land on a shaded square?

5. Answer…… • There are 8 shaded squares. • There are 20 total squares.

6. Example…… • What is the probability that it will NOT land on a shaded square? • Answer…… • There are (20-8) or 12 unshaded squares.

7. Example…… • What is the probability of selecting a queen out of a standard deck of 52 cards? • Answer…… • There are 4 queens in the deck. • There are 52 cards in the deck.

8. Example…… • An urn contains 3 blue balls, 5 red balls, and 2 orange balls. • A. Find • Find • Find • Answers…… A. B. C.

9. Fundamental Counting Principle…. • If one event can occur “m” ways and a second event can occur “n” ways, then total number of ways both events can occur is

10. Example…… • Katie has 2 pairs of pants, 4 shirts, and 3 pairs of shoes that can all match up and make an outfit. • How many different outfits can Katie make? • Answer….. • (2)(4)(3) = 24

11. Example…… • An urn contains 3 red and 5 blue marbles. Find the probability of selecting 2 blue marbles in a row if you do not replace the 1st one after it is selected. • Answer…… • You have 5 BLUE marbles. • You have 8 TOTAL marbles.

12. Example: Titanic P(3rdclass) P(survived) P(1stclass) P(died)

13. Example…… • A single card is drawn from a deck. • Find a. P(black ace) b. P(spade or diamond) • Answer: a. b.

14. Worksheet….