I'm learning through an introductory statistics textbook, and I just can't get the intuition when the textbook mentioned this for independent events $A$ and $B$:
$\bullet$ P(A|B) = P(A)
$\bullet$ P(B|A) = P(B)
$\bullet$ P(A AND B) = P(A)P(B)
I'm learning through an introductory statistics textbook, and I just can't get the intuition when the textbook mentioned this for independent events $A$ and $B$:
$\bullet$ P(A|B) = P(A)
$\bullet$ P(B|A) = P(B)
$\bullet$ P(A AND B) = P(A)P(B)
The usual definition of two events being independent is that
$$P(A \cap B) = P(A)P(B)$$
The conditional probability formula is
$$P(A|B) = \frac{P(A \cap B)}{P(B)}$$
(with a similar form for $P(B|A)$, just $P(A)$ on the bottom instead). The first two bullets will immediately follow. An example: if $A,B$ are independent,
$$P(A|B) = \frac{P(A \cap B)}{P(B)} \overset{ind.} = \frac{P(A)P(B)}{P(B)} = P(A)$$
(where $\overset{ind.} =$ denotes where we invoke the definition of independence as in the first lines of this post).