Counting and Probability

Culan O'Meara
Flashcards by Culan O'Meara, updated more than 1 year ago
Culan O'Meara
Created by Culan O'Meara over 6 years ago


Flashcards on Counting and Probability, created by Culan O'Meara on 09/29/2014.

Resource summary

Question Answer
Fundamental Principle of Counting When there are m ways to do one thing, and n ways to do another, then there are m×n ways of doing both. For example, if there are 3 colours and 3 sizes of t-shirt, then there are 9 combinations available.
Sample Space The set of all possible outcomes of an experiment. There are three types: list, tree diagram and two-way table
Two-way table A sample space for showing the combined outcomes of two independent events. For example a throw of a die and picking a card from a pack.
Probability Scale
Trial Any particular performance of a random experiment, e.g. one roll of a die
Outcome A result of a trial
Event Occurrence of one or more specified outcomes. If we are looking to land an even number on a die, rolling a 6 would be an example of an event
Relative Frequency = Experimental Probability An estimate of the probability of an event occurring based on outcomes of trials already carried out
Fair = Unbiased If all outcomes are equally likely to occur then the trial or experiment is considered to be fair or unbiased. For example, a fair die should land on heads around 50% of the time
Theoretical Probability = Probability Probability of an event happening found by dividing the number of desirable outcomes by the total number of possible outcomes. E.g. Probability of rolling a 3 on a fair die is 1/6 as there is one favourable outcome and six possible outcomes
Expected Frequency Estimate of how many times we'd expect an event to happen over a set number of trials Expected Frequency = (no of trials) x (relative frequency or probability)
Tree Diagram Used to write down all possible combinations for two or more trials. Example below is for flipping a coin two times
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