Question

Given P(A) = 0.22, P(B) = 0.24, and P(B|A) = 0.21, are A and B independent or dependent?

Answer 1

Answer: Dependent

Explanation:

Ignore P(A) = 0.22 as we don't need it.

The notation P(B|A) is the same as writing "P(B) given event A happened".

Since P(B|A) = 0.21 is different from P(B) = 0.24, this tells us that event A changes the probability P(B). Therefore event B is dependent on event A somehow. The chances of event B goes down if event A happens.

If A and B were independent, then both of these equations must be true

• P(A|B) = P(A)
• P(B|A) = P(B)