Conditional Probability and Multiplication rule

Question 1

Conditional probability - 2

Answer 1

• The probability of B occurs after A has occurred
• P(B|A) = P(A n B) / P(A)
• !!! P(B|A) ≠ P(A|B)

Question 2

Multiplication rule - 1

Answer 2

• P(A n B) = P(A) * P(B|A)

Question 3

Independence - 2

Answer 3

• Two events A and B are independent if P(A n B) = P(A) * P(B)
• Independence ≠ Disjointness

Question 4

Sampling and Small sample rule - 3

Answer 4

• Sampling with replacement: selections are independent events
• Sampling without replacement: selections are dependent events
• Small sample rule: when drawing a small sample from large population we treat selections as independent events

Question 5

Complement of at least one - 1

Answer 5

• P(at least one occurence of … ) = 1 - P(no occurence of … )