1.3 Counting Flashcards
The Probability of the Interserction of Independant Events
P(AnBnCn..Z)= P(A)P(B)P(C)*P(Z)
Whenever more than one indep events occurs, multiply their probabilities together
When to use rule 1
- 0.57 like this 0.43 hate that; randomly chosen 2, prob of both liking?
-quiz has 4 questions with 4 answers each, randomly answer, prob of all correct?
KEYWORD FOR RULE #1
RANDOMLY CHOSEN- means that A does not effect likeliness of B!
Multiplicative rule
basically used when need to find the number of ELEMENTS in the intersection of independant events!!!!!!!!!!!!!!!
Permutations
Order matters!
Pick
Arrange
One by one w/o replacements
Order
Combinations
Order doesnt amtter
Select
What is counting
Determingi elements in sample space
Steps to counting
- Figure out n(S) either with r^m or using nCr
- For n(A) break up itno simpler concepts (is there any laws we can use?)
- KEYWORDS?
-Randomly chosen: independant
-> or < use Box
-Select use Circle!
- Think is this ordered? If need be add an ordered combination
How to add order to combinations
HOW TO CHECK
nCr
n= total amount in group
r= how many objects do we want?
4 EVEN CARDS PICK 2 (4C2)
Basically it gives us all possible outcomes of this scenario
CHECK BY WRITING OUT POSSIBILITIES!!!
AIf a car is permanently chosen?
(1C1) like a king of diamonds
Draw a diagram for?
All dice and card questions
Perms can be written as?
COMBINATIONS
6X5X4
(6 1) (5 1) (4 1)
How to do pair questions?
Make a pattern to visualize
AABCD
SCENARIO
If all spots are the same?
Pick a leader!
SCENARIO
Two diff event types? Independant from one another?
Use the circle split in half, use the RULE #1