https://www.khanacademy.org/math/precalculus/x9e81a4f98389efdf:prob-comb/x9e81a4f98389efdf:addition-rule-prob-precalc/v/addition-rule-for-probability 2021-07-01T17:39:46Z Addition rule for probability Venn diagrams and the addition rule for probability Sal Khan video https://cdn.kastatic.org/googleusercontent/Bf6MZCeyotuvNzQ7zcv1XGuUDq3NjdIaP_dLZudyn_q7YhjU8t-GoNKQM_dtArCQk9WHBF6jU1uz_9bhYhbkKF8XnQ Addition rule for probability Venn diagrams and the addition rule for probability https://cdn.kastatic.org/ka-youtube-converted/QE2uR6Z-NcU.mp4/QE2uR6Z-NcU.mp4 643 Calculating probabilities of a complementary of an event and union of events https://www.khanacademy.org/math/ka-math-class-11/x0419e5b3b578592a:probability-ncert-new/x0419e5b3b578592a:axiomatic-approach-to-probability/v/probability-of-the-event-a-or-b-1 2025-03-01T15:52:37.13987578Z Probability of the event 'A or B' Let's use our understanding of sets and Venn diagrams to find probability of union of events. We first look at a concrete example and try to find the probability of event A or B. Through the result, we try to observe a pattern which we then generalise into a robust formula. We then prove that formula using axioms of probability discussed in previous videos. Ashish Gupta video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Probability of the event 'A or B' Let's use our understanding of sets and Venn diagrams to find probability of union of events. We first look at a concrete example and try to find the probability of event A or B. Through the result, we try to observe a pattern which we then generalise into a robust formula. We then prove that formula using axioms of probability discussed in previous videos. https://cdn.kastatic.org/ka-youtube-converted/Xa1RC-MZ9ws.mp4/Xa1RC-MZ9ws.mp4 356 Calculating probabilities of a complementary of an event and union of events https://www.khanacademy.org/math/ka-math-class-11/x0419e5b3b578592a:probability-ncert-new/x0419e5b3b578592a:problems-on-probability/v/probability-of-union-of-three-events 2025-05-30T12:59:32.180778541Z Probability of union of three events This video explains the formula for the probability of the union of three events (A or B or C). We'll use a Venn diagram to visualize the different regions representing the events and their intersections. By carefully considering each section, we'll derive the general formula: P(A U B U C) = P(A) + P(B) + P(C) - P(A and B) - P(B and C) - P(C and A) + P(A and B and C). This illustrates the inclusion-exclusion principle for three events. Ashish Gupta video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Probability of union of three events This video explains the formula for the probability of the union of three events (A or B or C). We'll use a Venn diagram to visualize the different regions representing the events and their intersections. By carefully considering each section, we'll derive the general formula: P(A U B U C) = P(A) + P(B) + P(C) - P(A and B) - P(B and C) - P(C and A) + P(A and B and C). This illustrates the inclusion-exclusion principle for three events. https://cdn.kastatic.org/ka-youtube-converted/Ikoblkv_wrY.mp4/Ikoblkv_wrY.mp4 268 Calculating probabilities of a complementary of an event and union of events https://www.khanacademy.org/math/precalculus/x9e81a4f98389efdf:prob-comb/x9e81a4f98389efdf:addition-rule-prob-precalc/a/addition-rule-for-probability-basic 2026-03-06T16:30:33.181933133Z Addition rule for probability (basic) article https://www.khanacademy.org/math/class-10-tg/x6d741825a19c63c4:probability/x6d741825a19c63c4:complementary-events-and-probability/e/complementary-events-and-probability 2025-12-30T07:05:15.972746521Z Complementary Events and Probability In this exercise, we will learn about complementary events and probability. For any event E, P (E) + P (E' ) = 1, where E' stands for "not E". E and E' are called complementary events. In general, it is true that for an event E, P(E' ) = 1 – P(E). Khan Academy exercise