Probability Flashcards
What is probability?
Probability is about estimating or calculating how likely or ‘probable’ something is to happen.
The chance of an event happening can be described in words, for example ‘certain’, ‘impossible’ or ‘likely’. In maths, probabilities are always written as fractions , decimals or percentages with values between 0 and 1.
How do you find simple probability?
A simple probability is calculated by dividing a specific outcome by all the possible outcomes. For instance, when flipping a coin, there are two outcomes: heads or tails. To find the probability of getting either heads or tails, divide one outcome (1) by the two possible outcomes (2). Dividing 1 by 2 results in
Probability = the number of ways of achieving success. the total number of possible outcomes. For example, the probability of flipping a coin and its being heads is ½, because there is 1 way of getting a head and the total number of possible outcomes is 2 (a head or tail). We write P(heads) = ½.
What is Conditional Probability?
Conditional probability is defined as the likelihood of an event or outcome occurring, based on the occurrence of a previous event or outcome.
Conditional probability: p(A|B) is the probability of event A occurring, given that event B occurs. … Example: the probability that a card drawn is red (p(red) = 0.5). Another example: the probability that a card drawn is a 4 (p(four)=1/13). Joint probability: p(A and B). The probability of event A and event B occurring.
