Probability - The Basics Flashcards
What does P (A n B) mean?
The probability of A AND B occurring.
What does P (A U B) mean?
The probability of A OR B occurring.
What is the formula for calculating the probability of A OR B happening?
P (A U B) = P(A) + P(B) - P (A n B)
What is a mutually exclusive event?
When P (A n B) = 0, which means that A and B cannot occur at the same time.
e.g. tutoring and sleeping, haha.
What does P (A’ n B) mean?
The probability of event A NOT occurring and event B occurring.
What does P (A n B’) mean?
The probability of event A occurring and event B not occurring.
What is an independent event defined by?
P(A) x P(B) = P (A n B). If it is not equal, it is dependent.
What is an dependent event?
When the probability of an event happening relies on the probability of the other.
What is an independent event?
Events which occur with no relation to any others (in terms of probability)
What is the conditional probability formula?
P (A | B) = P (A n B) / P(B)
Where:
P (A | B) = the probability of A happening given that event B has already happened?
P (A n B) = the probability of getting A and B at the same time
P (B) = the probability of B happening
What is conditional probability?
Given that EVENT B has already happened in the past, what is the probability of EVENT A now happening? ( ‘|’ - means “given that”)
Why do experimental and theoretical probability values differ?
Due to chance variation, which is due to the limited number of trials. The more trials there are, the closer the experimental probability will be to the theoretical probability.
Why do we use simulations?
A simulation would allow someone to see that there is variation for the experimental probability for sets of 30 trials.
