E(X) & Var(X) (Discrete) What does E(X) mean and how do I calculate E(X)? E(X) means the expected value or the mean of a random variable X For a discrete random variable, it is calculated by: L...
Discrete Random Variables What is a discrete random variable? A random variable is a variable whose value depends on the outcome of a random event The value of the random variable is not known unti...
Probability Formulae What is meant by probability formulae? If you have seen any of the other Revision Notes on probability, almost every one contains a formula These however are often disguised in...
Further Venn Diagrams What do you mean by further Venn diagrams? The Venn diagrams used here are no more complicated than those in the first Venn Diagrams revision note, however questions may use s...
Further Tree Diagrams What do you mean by further tree diagrams? The tree diagrams used here are no more complicated than those in the first Tree Diagrams revision note, however more detailed use o...
Set Notation What is set notation? Set notation is a formal way of writing groups of numbers (or other mathematical entities such as shapes) that share a common feature – each number in a set is ca...
Combinations What is the difference between permutations and combinations? A combination is the number of possible arrangements of a set of objects when the order of the arrangements does not matte...
Permutations Are permutations and arrangements the same thing? Mathematically speaking yes, a permutation is the number of possible arrangements of a set of objects when the order of the arrangemen...
Arrangements How many ways can n different objects be arranged? When considering how many ways you can arrange a number of different objects in a row it’s a good idea to think of how many of the ob...
