Backlinks and PageRank. What's the Relationship?

Thread Title:
Relationship Between PageRank and Number of Backlinks
Thread Description:

On the forums or by email I am often asked the following sort of question: "How many Backlinks do I need to get in order to have PR5?". The answer is simple and always the same one: "This question cannot be answered because the PR doesn't only depend on the number of backlinks, it also and above all depends on the PR of each of those links...". Or to put it differently, a page can have PR5 with a single backlink whereas another one can have 3,000 backlinks and PR5 too.

As a result it seems useless to carry out this type of analysis... Except if one is to compare the results in the long term. That's what I have been doing over the past eight months by analysing tens of thousands of pages. For each data I get the number of backlinks and the PR of the page with those links. The data do not come from a tool using a Google Toolbar crack but from the "MyWri" tools on WebRankInfo which enables each WebRrankInfo member to instantly get the PR and the number of backlinks of 10 chosen sites (many other free SEO tools are also freely provided).