Introduction to Probability

1
Introduction to Probability
2
Probability Quiz

• Assign a probability to each event.
• You will miss a day of school this year.
• You will get an A in math.
• A tossed coin will land tails.
• You will gain 10 pounds this year.
• You will live to be 100 years old.
• The sun will rise tomorrow.

3
Probability Quiz

• The next President of the United States will be
  over 21 years old.
• A card drawn from a standard deck will be a club.
• You will take a space trip to the moon.
• The next baby born in this state will be a girl.
• You will listen to your iPod today.
• You have type D blood.

4
Definition of Probability

• The probability of an event is a number between 0
  (0) and 1 (100) inclusive that indicates the
  likelihood of the event occurring.
• 0 50
  100
• impossible
  certain

5
Probability Game with Sum of Dice

• Goal To win the most rolls.
• Directions Working with a partner,
• One player chooses odds while another player
  chooses evens.
• Roll the dice. Sum the faces.
• Record the sum on either the odd or even
  scorecard.
• Repeat 99 more times.

6
Definition of Probability

• The probability of event A occurring is given by
• number of ways A can occur
• P(A) total number of outcomes

7
Probability with Cards

• P(E)
• P(E)
• P(S)
• P(vowel)
• P(second half of alphabet)
• P(second half or vowel)
• P(second half and vowel)
• P(before I and vowel)
• P(before I or vowel)

8
Probability Game with Sum of Dice

• Is this game fair?
• How many different ways are there to roll the
  dice?
• How many different ways are there to roll an even
  number?
• How many different ways are there to roll an odd
  number?

9
Calculation Probabilities of Sums
10
Calculating Probability

• P(2)
• P(3)
• P(4)
• P(5)
• P(6)
• P(7)

• P(8)
• P(9)
• P(10)
• P(11)
• P(12)

11
Is this game fair?

• Circle the different ways to roll even numbers in
  the chart.
• Square the different ways to roll odd numbers in
  the chart.
• How can you determine if this game is fair?

12
Experimental Probability

• Record the number of times you rolled each of the
  sums on the tally sheet.
• Using your tally sheet, calculate the
  probabilities for rolling a sum of 2, 3, 4, 5, 6,
  7, 8, 9, 10, 11, 12
• Create a bar graph of the different sums
• How can you determine if this game is fair?

13
Probability Game with Product of Dice

• Goal To win the most rolls.
• Directions Working with a partner,
• One player chooses odds while another player
  chooses evens.
• Roll the dice. Calculate the product of the
  faces.
• Record the product on either the odd or even
  scorecard, depending upon the product.
• Repeat 99 more times.

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Is this game fair or unfair?

• If you were even and won, then raise your hand.
• Is this game fair?
• Prove that this game is either fair or unfair.

15
Create your own game

• Working with your partner, create your own game.
• Explain the strategy you would want to use to win
  your game using probability.