Does page rank affect SERP? Suppose i have a webpage with PR3 like example.com/web.html. So will it get higher SERP as compared to other low or zero PR webpages?
PR has an effect on SERPs but no just PR alone. If a lower PR page has more relevant links to it then it will rank higher. You cannot rely on PR alone to rank in SERPs.
Even if PR have any effect on SERP ranking, it would be really small. And PR is not the only thing that effects rank; there are important factors like content quality, backlink quality, no of pages etc etc.
Lots of misinformation here. It's probably best if you just read the PR formula - http://en.wikipedia.org/wiki/PageRank. PR does indeed affect SERP, but not in the way that most people imagine. If you have 10 pages on your own website, and one of them is a PR 4 (likely the home page), and the pages all link to one another, then that PR 4 page is passing it's PR to the other pages on your site, therefore improving their SERP. The PR of a single page won't help that page's own SERP, it will only help the SERP of pages it links to. On a related note, the max PR for a single domain can't be more than the # of pages. So if you have a 1-page AdSense spam blog site, you're never going to be higher than PR 1.
PR makes little difference in reality despite what SEO bods say. I have a number of sites with no PR and yet rank for no1 in serps for certain keywords
If you have a webpage, as you said pr3 and another webpage with lower PR, yours will rank higher is SERP. And if your webpage have backlinks with higher PR, yours will rank higher in SERP, in compare to others with lesser PR backlinks. The importance of PR lies here.