The formula for conditional probability (AQA GCSE Statistics): Flashcards
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Practise the cards
10 cards from this deck
What is the formula for conditional probability?
What is the formula for conditional probability?
P(B|A) = P(A and B) / P(A)
How do you interpret P(B|A)?
How do you interpret P(B|A)?
Probability of B given A has occurred.
How to calculate P(B|A) using P(A) and P(A and B)?
How to calculate P(B|A) using P(A) and P(A and B)?
P(B|A) = P(A and B) / P(A) = 0.3 / 0.6 = 0.5
What does the vertical line in P(B|A) signify?
What does the vertical line in P(B|A) signify?
It means 'given that' or 'knowing that'.
If A and B are independent, what is P(B|A)?
If A and B are independent, what is P(B|A)?
P(B|A) = P(B)
In a Venn diagram, what does the overlap represent?
In a Venn diagram, what does the overlap represent?
Outcomes where both A and B occur.
Find P(A and B) if P(B|A) = 0.4 and P(A) = 0.5.
Find P(A and B) if P(B|A) = 0.4 and P(A) = 0.5.
P(A and B) = 0.4 * 0.5 = 0.2
What is a common mistake with conditional probability?
What is a common mistake with conditional probability?
Confusing P(B|A) with P(A|B).
How do you find P(B|A) using a Venn diagram?
How do you find P(B|A) using a Venn diagram?
Count outcomes in A and B, divide by outcomes in A.
How to calculate P(B|A) using P(A) and P(A and B)?
How to calculate P(B|A) using P(A) and P(A and B)?
P(B|A) = P(A and B) / P(A) = 0.1 / 0.2 = 0.5