A-Level Maths · Statistics
Probability Distributions
What is it
A probability distribution describes all the possible outcomes of a random variable along with their probabilities — A-Level covers discrete random variables, expected value (mean), and variance of a distribution.
Why it matters
Probability distributions are the mathematical model behind every statistical test that follows — understanding what a distribution represents is essential before applying the binomial or normal distribution to real problems.
Exam tip
Always check that the probabilities in a distribution sum to exactly 1 before proceeding with a calculation — this quick check catches most set-up errors in probability distribution questions.
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