What is ideal developer/tester ratio?

While some companies manage with 1 tester per 10 or more developers other companies have 3 testers per developer. Does this mean the later companies come out with better quality products compared to former or is it just that the team is not properly organized. My dream team will have test developer ratio of 5:6, well why such a strange ratio. According to me the code developed by 2 developers can be reviewed (or inspected) by 1 testers and code developed by 3 developers can be tested by 1 black box tester. So for 6 developers we need 2 black box testers and 3 White box testers. The job of white box tester is the code review and automation, while black box testers job include creation of test cases, test execution. Many firms does not like to have white box tester (code reviewers), I found that independent code reviews done by non-developers help identifying large number of bugs early in development.