Probability Formulas

Question 1

What is P(A)

Answer 1

probability an outcome will belong to event A

Question 2

What is A^c

Answer 2

Complement. all outcomes not included in event A

Question 3

Complement formula

Answer 3

P(A)^c = 1 - P(A)

Question 4

Or formula

Answer 4

P(A u B) = P(A) + P(B) - P(A n B)

Question 5

And formula

Answer 5

P(A n B) = P(A) x P(B|A) OR P(B) x P(A|B)

Question 6

What is conditional probability?

Answer 6

The probability of belonging to B given we know it belongs to A. Denoted as (B|A). For example what is the probability of a card being a face card knowing that it is Red -> P(F|R)

Question 7

What is Disjoint

Answer 7

When A and B are mutually exclusive, Ie no one said yes to both. P(A n B) when disjoint is 0

Question 8

Independence

Answer 8

When A and B are independent, P(A n B) = P(A) * P(B)

Question 9

Conditional probability formula

Answer 9

P(A|B) = P(A n B) / P(B)