1. Probability
Simple and Compound

3. Probability of Simple Events
Simple Event – one outcome or collection of outcomes
Probability – the chance of that event happening
Outcome – any one of the possible results of an action
P(event) = 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑓𝑎𝑣𝑜𝑟𝑎𝑏𝑙𝑒 𝑜𝑢𝑡𝑐𝑜𝑚𝑒𝑠 𝑛𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑝𝑜𝑠𝑠𝑖𝑏𝑙𝑒 𝑜𝑢𝑡𝑐𝑜𝑚𝑒𝑠
P(rolling an even number) = P(5) =
P(rolling an odd number)= P(not prime) =

4. Probability of Compound Events
Mutually Exclusive - Events that cannot occur at the same time P(5 or 6) = P(3, 4 or 5) = P(even or 3) =
Probability of Mutually
Exclusive Events
P(A or B) = P(A) + P(B)
P(rolling a 2 or a 3 on a die) = P(2) + P(3) = 1 3

5. Probability of Compound Events
Mutually Inclusive - Events that cannot occur at the same time P(multiple of 2 or even) = P(less than 5 or odd) =
Probability of
Inclusive Events
P(A or B) =
P(A) + P(B) – P(A and B)
P(black card or 10) = P(black) + P(10) – P(black and 10) =

6. Example:
A card is drawn from a standard deck of playing cards. a. Find the probability of drawing a king or a queen. b. Find the probability of drawing a king or a spade.

8. Probability of Compound Events
Independent Events- Events that do not affect each other. Made up of two or more simple events. Dependent Events- Events in which the outcome of one will effect the other.
Probability of
Independent Events
Outcome of first event does not affect outcome of second.
P(A and B) =
P(A) ⋅ P(B)
Example: rolling a 6 on a die and then rolling a 5
Dependent Events
Outcome of first event does
affect outcome of second.
P(A) ⋅ P(B following A)
Example: without replacing the
first card, choosing an ace and
then a king from a deck of cards

10. Example:
Find the probability that you will roll a six and then a five when you roll a die twice. A bag contains 3 red marbles, 2 green marbles, and 4 blue marbles. Two marbles are drawn randomly from the bag and not replaced. Find the probability that both marbles are blue.

11. Probability of Compound Events
Examples-
What is the probability of rolling a 6 and a coin landing on heads?
Probability of rolling a six =
Probability of flipping heads =
Probability of both =

12. Probability of Compound Events
Examples-
What is the probability of dropping a coin down 12 stairs and it landing heads up on the 5th stair?
Probability of flipping heads =
Probability of landing of the 5th step =
Probability of both =

13. Probability of Compound Events
Examples-
There is a bag filled with 10 marbles: 6 red, 1 blue, and 3 green. What is the probability of randomly picking out a red marble then a green marble?
Probability of red =
Modified prob of green =
Probability of both =

14. Probability of Compound Events
Examples-
There is a bag filled with 10 marbles: 6 red, 1 blue, and 3 green. What is the probability of picking a red then a red then the blue marbles?
Probability of red =
Modified prob of red =
Modified prob of blue =
Probability of all =