Suppose that the proportion Theta of defective items in a large manufactured lot is known to be either .1 or .2 and the prior p.f. of Theta is as follows:

E(.1)=.7 and E(.2)=.3

^Those E's are a greek letter in the text, I'm guessing representing a prior distribution.

Suppose also that when 8 items are selected at random from the lot, it is found that exactly two of them are defective. Determine the posterior p.f. of Theta.

Any help?? This is our first day doing this so I am very lost...