Does Google PR is actually based on number of Backlinks?

[sammrat]

I have tested many websites in the past few days, Google's Page Rank is not based on nummber of backlinks to the sites.
I often see many SEO Experts say that Good PR can be obtained basis on backinks, i ask them HOW?

1)
I tested a website which is 7 years old and the site does not contain any meta tags, any content on the webpage (found only images without any ALT tags), number of backlinks are 10. But the site still holds Page Rank 3. Can a genuine SEO Expert answer this to me?

2)
I tested one more webiste, which is 1.3 years old and the site contains above average meta tags, but the number of backlinks to the site are 9 crores and 72 lacs types but the site still holds Page Rank 4. How is this possible? As per many articles written by various experts, if you hold above 1 crore backlinks to your site, then the PR would be above PR9 types.

Please I request only genuine SEO Experts answers this and rest excuse...

[marketraisecorp]

In terms of link building,Quality of links matters than quantity.If a site has a lot of backlinks and are not relevant,then it is of no use.One quality backlink is much much better than 10 non relevant backlinks.

[lenesyn]

PR are based on quality of back links compared to quantity.. You have higher chances of getting higher PR value on back links with the same niche because google gives more weight with those kinds of back links.. When talking about quality we are talking about relevancy..