Originally Posted by

**Atomic_Sheep** Hi, I'm pondering on the following problem and I'm not quite sure how to tackle it even though it looks like I've covered this in the past.

If y is the random variable that represents the type of animal where

0 = dog

1 = elephant

how does **p(x)** = *p(x|y=1) * p(y)* + *p(x|y=0) * p(0)*

I'm trying to conceptually visualise what each of these parts means i.e. what does p(x|y=1) * p(y) mean? and what does p(x|y=0) * p(0) mean by themselves?

The way I see it, we are basically multiplying the distribution which defines elephants by the probability that our distribution is of an elephant but that's just obvious and doesn't outline the concept behind this multiplication which is where I'm drawing a blank. (That's right isn't it? it's the distribution of the elephant?) Is there some sort of visual representation that would show this? I think I'm better at understanding this stuff if I see a graph or something but really, I'd be very appreciative of any form of explanation.