probability Flashcards
What is a two way table and how can it be used to find probability?
A grid with with one condition selection going across and one going down. All cells in the table can be counted and all cells that fulfil the required criteria can to - the criteria fitting cells can then be represented as a fraction of the whole number which is the probability
What is linear interpolation?
When asked how many entities will satisfy a certain criteria (usually something completed after x time) that spans midway through a class, it can be used to find how many entities will be applicable from that class. it assumes an equal distribution within the class
What does π mean?
universal set - the bits not in the circles of a venn diagram but in the box.
What does U mean?
Union in venn diagrams - ie this section or this section
What does β© mean?
intersection or and. on a venn diagram something has to be in both categories
Have a look at some of these Venn diagram classifications:
When filling in a venn diagram, where should you start?
From the most intersections and work your way out, subtracting the multiple criteria identifiers from the singular as you spiral out
when are 2 events mutually exclusive?
when they cant happen at the same time
What are the formulaic conditions for mutual exclusivity?
- P (A and B) = 0
- P (A or B) = P (A) + P (B)
what does it mean if events are independent?
Whether one event happens does not affect the probability of the other happening
what is the formulaic condition for events being independent?
- P (A and B) = P (A) X P (B)
How do you note a conditional probability?
P (B/A) - probability that B happens given that a has happened
what is the formula for a conditional probability?
P (B/A) = P (AβB) / P (A)
What are the methods for finding conditional probability?
- Use the formula (no diagram)
- Deduce from a two way table
- Multiply along branches of a probability tree
What is a sample space diagram?
itβs a grid representing every possible outcome used to decide possibility
how do you determine conditional probability from a venn diagram?
identify how many cases identify in total with the first condition then write as a fraction the no. cases from the second condition that agree
what is a random variable?
When each of a collection of values is assigned a probability of occuring
What does a random variable X represent?
A single experiment or trial that consists of outcomes with a probability for each
What are the ways for expressing a mapping from outcomes to probabilities?
as a function or as a table:
How can you find probabilities on a table when a function is given in terms of k?
Remember all probs. on bottom row must sum to 1 and solve algebraically for k.
substitute k back in.
What is a uniform distribution?
where every outcome has equal probability of happening
