currently i have a site which doesnt have any incoming link. but suppose if i get a link for a page of PR 8 ( which has only 3 out link) so what do u think what will be the PR of my site after indexing by google
Sam by indexing by Google, I assume you actually mean after the link from the hypothetical PR8 is realized / recognized?
I honestly don't have a good educated guess, but I can point you to a DP thread that has PR predictors. This won't do you much good until your site is indexed by Google and any backlinks are showing up pointing to your site. http://forums.digitalpoint.com/showthread.php?t=7881
that rustybricks tool sucks. its only a joke nothing else. actually there is no way to predict PR. but on the basis of Compar's PR Calculation chart. if you get a BL from a PR8 Page(Mind the page, not the site) you should get somewhere around PR of 6. http://www.compar.com/infopool/articles/PR-calculation.html But I doubt, that is always the case.
a question please: is it better to have only 3 out links on a high PR site for linking? More is not good? why? Iam asking, because: I have a PR 6 Site and the others are only mostly PR5, so I thougt it is a good Idea to link from my PR6 site to all my others Sites (8 or 9 Links)
Few people think that PR of a page is evenly distributed through out the links on that page. so more links on the page, less weightage you'll get.
if you have only backlink from PR 8 and that page has only 3 ougoing links. Your site will be passed PR 8 / 3 = 2.666 and it will show Toolbar PR as 3 but your internal linking will also effect on PR. IF you have very good interlinked site it will be higher