Experiments, outcomes, sample spaces and events, classical probability and relative frequency, the basic laws, the addition rule, mutually exclusive events and Venn diagrams.
5 narrated scenes. Press play, listen and read along — the points appear as they are explained. Use ‹ Prev / Next › or the scene bar to jump to any scene.
Probability turns “likely” and “unlikely” into numbers between 0 and 1 — and set language and Venn diagrams make the rules visual.
Narration uses your device’s built-in voice. No sound? Switch to “Captions only” — the captions advance on their own.
Copy these into your notebook in your own words — that is how they stick.
Experiment, outcome, sample space S, event (a subset of S).
P(A) = n(A)/n(S) (equally likely outcomes, S finite).
successes ÷ trials estimates probability.
ΣP = 1; 0 ≤ P ≤ 1; P(A′) = 1 − P(A).
P(A ∪ B) = P(A) + P(B) − P(A ∩ B).
P(A ∩ B) = 0.
Rectangle = S; circles = events; regions sum to 1.
Use 1 − P for “at least one” and “not”.
3 quick games on this lesson. Earn XP and badges as you play — your best score for each game is saved. Games are for practice and do not change your exam readiness. More games in the Additional Mathematics Arcade.
8 items modelled on real CSEC Paper 1 questions. Choose one answer for each, then check. Aim for 80% or better. Work each item on paper first.
Write full answers, then reveal the mark scheme and tick the points you earned (22 marks in total). Show all your working — method marks count. Your answers are saved on this device.
Question 1 [13 marks]
Events A and B are such that P(A) = 0.6, P(B) = 0.5 and P(A ∪ B) = 0.8.
(a) Find P(A ∩ B). [2]
(b) Draw a Venn diagram showing the probability in each region. [3]
(c) Find P(A′ ∩ B) and P((A ∪ B)′). [3]
(d) Are A and B mutually exclusive? Give a reason. [2]
(e) A fair die is rolled twice. Find the probability that the sum is 8 or both rolls are the same. [3]
Question 2 [9 marks]
In a music club, 0.30 of the members play only piano, 0.15 play both piano and guitar and 0.40 play only guitar. The rest play neither.
(a) Find the probability that a member plays neither instrument. [2]
(b) Find P(piano) and P(guitar). [2]
(c) Show that P(piano ∪ guitar) = P(piano) + P(guitar) − P(both). [3]
(d) The club has 120 members. How many play at least one instrument? [2]
Find these in your own past-paper booklets for extra timed practice. Items above are written in the style of these papers; any adapted from a specific question say so.