



 
Chris, One way to approach this problem is to try some extreme numbers.
Has this person really made over half of the postings? I don't think so! The second way is clearly wrong. Harley
Lets say that on one forum, a memebr has made 52 posts out of the 412 posts This means: of the total posts to both forums, what proportion are made by the person?
This is obviously right, as you find the numbers needed and
What you really want to know is "why is this one wrong?" The simple answer is "because you are not doing what was asked for, and what you did is not mathematically equivalent." To cultivate a better feeling for why you should not believe in the second method, consider an extreme case. Suppose in the second forum there is only one post, and our friend made it (100%). It is surely clear that the overall percentage should not be and that this figure is irrelevant for most purposes. Good Hunting!  


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