Among the examinees in an examination30%, 35% AND 45% failed in statistics, in mathematics,and in at least one of the subjects respectively.An examinee is selected at random. Find the probabilities that
a.He failed in mathematics only
b.He passed in statistics, if it is known that he has failed in mathematics.

Having a Venn Diagram would not doubt help you a lot here.

http://p1cture.me/images/50073645766463637107.png

Here, I made it for you. The three colours together represent 45%.

So, you get an equation here.

I denoted 'x' by the number of examinees who failed in both subjects.

Can you try to answer your questions now? Post your answers! :)