Y2, C2 - Conditional Probability Flashcards
Formula for independent event
A n B = A x B
A l B = A
What are independent events
When one event remains unaffected by the occurrence of another event
What are mutually exclusive events
When two events cannot occur at the same time
Formula for mutually exclusive events
A n B = 0
A u B = A + B
Formula for ‘given that’
A l B = (A n B) / B
What is a sample space
The set of all possible outcomes
What is an event
A set of one or more outcomes (that is a subset of the sample space)
What is the formula for the addition law
A u B = A + B - A n B
What is complement
’
A’ (NOT A)
What is union
u
A OR B
What is the formula for P(B l A)
P(B l A) = P(A n B) / P(A)
What does P(B l A’) mean
What is the chance that B happens given that A doesn’t happen
When is P(B) = P(B l A)
When B and A are independent
What does P(A) * P(B l A) equal
P(A n B)
P(A) = 0.5, P(B) = 0.5, P(A n B) = 0.4
Find P(B l A)’
0.1 / 0.4 = 1/4
