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Summary for Probability

Summary of Probability
Probability: Likelihood of an Event occurring
𝑃(𝐸) =
#𝑡𝑖𝑚𝑒𝑠 𝑒𝑣𝑒𝑛𝑡 𝐸 𝑜𝑐𝑐𝑢𝑟𝑠
#𝑎𝑙𝑙 𝑝𝑜𝑠𝑠𝑖𝑏𝑙𝑒 𝑑𝑖𝑓𝑓𝑒𝑟𝑒𝑛𝑡 𝑒𝑣𝑒𝑛𝑡𝑠
Not P(E) is probability that P(E) will not occur.
Not P(E)=1 – P(E)
Mutually Exclusive events: Cannot happen at once
P(A or B)=P(A) + P(B)
Mutually Inclusive events: Can happen at the same time or they don’t affect each other if they happen
at different times
P(A and B)=P(A)*P(B)
If there is a case where events are inclusive, then
P(A or B)=P(A) + P(B) – P(A and B)
Solving Probability Problems
Step 1: Find the data
Step 2: Set up the probability
Step 3: Solve for x