What is General Multiplication Rule?

General Multiplication Rule

Always works.

P(A and B) = P(A) * P(B|A)
Example 4:

P(A) = 0.20, P(B) = 0.70, P(B|A) = 0.40

A good way to think of P(B|A) is that 40% of A is B. 40% of the 20% which was in event A is 8%, thus the intersection is 0.08.