Probability

An ordinary six sided dice is rolled 300 times and lands on five 120 times. Do you think the dice is fair? That is a real two mark question from a specimen Core paper, and answering it needs three separate ideas: what probability a fair dice gives, how many fives that predicts in 300 rolls, and how far an actual result can drift from a prediction before you should be suspicious. Fifty is expected, 120 was observed, and the gap is far too large to be luck.

You will use the vocabulary of probability and the probability scale, find probabilities from theoretical models and from relative frequency, work with expected frequency, compare experimental data with theoretical probabilities, understand why repeating an experiment gives different outcomes and why a larger sample gives better estimates, build sample spaces for one event and for two successive events, handle mutually exclusive and exhaustive outcomes, use Venn diagrams to work out probabilities, and calculate the probability of independent combined events including with tree diagrams. On the Extension Tier you add the addition rule for mutually exclusive events, the multiplication rule for independent events, and conditional probability.