1. C.3 Section 2.6-2.7 WHAT IS PROBABILITY?
Probability : is the likelihood of an event
occurring.
It can be expressed as a fraction, decimal or percent.
Probability for event is

2. Range of Possible Probabilities
Less likely More likely .5
50% 1
Equally Likely and Unlikely
Impossible Event
Certain Event
Rolling a 7 on a number cube
Rolling a number less than 7 on a number cube
Getting a head when flipping a coin

3. Ex. 1 – Rolling a Standard Number Cube
Find
Ex. 2
Ex. 3

4. A jar contains 15 blue marbles, 10 red, 5 green and 5 yellow.
Ex. 4
Ex.5
Ex. 6

5. Probability with Standard Deck of Cards
A card is selected at random from a standard deck of 52 cards. What is the Probability of selecting a 3?
A card is selected at random from a standard deck of 52 cards. What is the Probability of selecting a 2 or a 5?

6. Probability with Standard Deck of Cards
A card is selected at random from a standard deck of 52 cards. What is the Probability of selecting a Face Card?
A card is selected at random from a standard deck of 52 cards. What is the Probability of selecting a Spade?

7. Experimental Probability
Quality control inspected 500 belts at random.
They found no defects in 485 belts.
What is the probability that a belt selected at random will pass quality control?

8. Now You Try
Find each probability for the roll of a number cube.
1. P(4) 2. P(not 4) P(odd)
4. You spin the following spinner.
P(red) b) P(a number less than 6)
c) P(a number greater than or equal to 6)
d) P(Not a multiple of 3)

9. Extending the Idea of Probability
Suppose you roll a number cube 60 times. How many times should you get a 5?
Suppose you spin the following spinner 100 times, how many times should you get a 6?

10. Extending Ideas of Probability
Using the spinner at the left, answer the following questions.
Give an example of a certain event.
Give an example of an impossible event.