Topic 3 - Probability Flashcards
1
Q
What are permutations
A
- Number of ways to choose x objects from a total of n objects without replacement
- Order matters as the same x objects selected in a different order is considered a different outcome
2
Q
What is the formula for permutations
A
- n! / (n-x)!
3
Q
What are combinations
A
- Number of ways to choose x objects out of n without replacement
- Without distingushing between the different orders in which they could be chosen
4
Q
What is the formula for combinations
A
- n! / x!(n-x)!
5
Q
What is the definition of a random experiment
A
- The process of observing something uncertain
6
Q
What does collectively exhaustive mean
A
- If the union of all possible events is equal to the sample space
7
Q
What does the complement of an event mean
A
- The set of all basic outcomes in the sample space that do not belong to A
- Not A
8
Q
What are the 3 different ways of assessing probabilty
A
- Classical Probability
- Relative Frequency Probability
- Subjective Probability
9
Q
What is the calculation for classical probability
A
- P(A) = number of satisfying outcomes / number of outcomes in the sample space
10
Q
When is classical probability suitable
A
- When all outcomes in the sample space are equally likely to occur
- E.g. rolling a dice
11
Q
What is the calculation for relative frequency probability
A
- P(A) = number of outcomes in population that satisfy event A / number of outcomes in the population
12
Q
What is subjective probability
A
- An individual opinion or belief about the probability occurrence
13
Q
What does x! mean
A
- The total number of possible ways of arranging x objects in order
14
Q
What are joint and marginal probabilities
A
- Marginal: P(B), P(A) etc
- Joint: P(A u B) etc
15
Q
What are the two probability rules
A
- P(Not A) = 1 - P(A)
- P(A u B) = P(A) + P(B) - P(A n B)
16
Q
What is the conditional probability formula
A
- P(A|B) = P(A n B) / P(B)
- If A and B are swapped then P(B) becomes P(A)
17
Q
What is the formula for Bayes’ rule
A
- P(A|B) = P(B|A) * P(A) / P(B)
18
Q
Write out a template for a joint probability table
A
probability powerpoint
