Probability as a Measure of a Sample Space
Core study note
Original study note aligned to the current AMAT 19 course outline
A probability model starts with a sample space of possible outcomes and events that select subsets of that space. For equally likely finite outcomes,
P(A) = |A| / |S|.
Keep the numerator and denominator tied to the model: the numerator counts outcomes in the event, while the denominator counts outcomes in the active sample space. Exact fractions preserve structure that can disappear if everything is rounded early.
Probability values must stay between 0 and 1, and the probability of the entire sample space is 1.