Question

If A and B are independent events, then it must be true that P(ATB) = P(A).

Answer 1

well, let's take a look at two independent events

A)  the potato is hot

B) it's raining

now, the potato could be hot whether is raining or not, A is totally independent of B, so what's the probability of "the potato being hot, GIVEN that it's raining" P(A | B)  is the same as if it wasn't raining, or P(A), the fact that B occurred, doesn't affect A at all, the potato is hot regardless, rain or not.  So P(A | B) = P(A).

Answer 2

Yes it has to be true

Hope this helps :)