Re: Q20
There is an analogy that may be enlightening, which I thought of because of the presentation of the first part of this course.
Suppose you have a large number of urns each containing a large number of black and white balls in varying proportions. You are told how many urns there are with each proportion.
Then you go up to one of the urns and take out a ball which you find is black. The question is how likely it is that specific urn has each particular fraction of black balls.
