Probability Flashcards
What is probability?
Probability is about estimating or calculating how likely or probable something is to happen. They are normally written as fractions or decimals between 0 and 1, or percentages between 0% and 100%.
How do you calculate probability?
Probability = the number of ways the event can occur / the total number of possible outcomes.
How do you calculate the probability of something not happening?
If the events are mutually exclusive (they cannot happen at the same time) then the probabilities must add up to 1, meaning you can do 1 minus the probability of it happening.
What is relative frequency?
It is where you conduct an experiment to estimate probability e.g. if I flipped a coin a times and I got b heads then the relative frequency of getting a head would be b/a.
What is the product rule?
It states that if there are n number of outcomes for a event and m number outcomes for b event then the number of outcomes for both of the events will be nm.
If there is a a/b chance of one event happening and a c/d chance of another event happening, what is the chance of both these events happening.
ac/bd
If the two events are not independent (if one event affects the probability of the other) then how do you find the general probability?
You draw a tree diagram and you vary the probability of the second event occurring.
