I mean, if I get a backlink from a site that has a PR4, but from a page that isn't ranked at all in that same website, Will it increase my Page Rank?

Thanks,

i think you can check if there are many links on this site,
if so, it little effect the pr with linking from this site
usuall,if some boday click the links and visit your site,it will consider a backlink by google.
you can check these sites for your reference

Hi,

Ya you will get the little benefit of that site's PR.
But, If you able to get the back link from any site whose back link page has pr1 or 2 than it will be more effective for your site rather than this back link

if the page that gives you the link has a page rank of 0, then there's no page rank to pass on to you. that's my understanding.
however, i do think there are still other factors besides just pagerank that google takes into account to measure that link coming from a website of pr 4 but a page inside with pr 0 - so I believe the link still adds something in favor to your website; though i don't know how it is calculated. it may not increase you actual pagerank but may be factored in for the purposes of your search engine page results.

if the page is topically relevant to your website for example, or if the website that is giving you the link has a lot of Global link popularity, and also if the anchor text of the link are your keywords for the search being conducted, I assume it passes something....

Ya, you will still get PR from that web, but it's not really that significant. You should post in a high rank PAGE to gain PR.

When you are trying to get link exchange, make sure that the link exchange page has PR and get indexed already.

yes page rank assign to each web page