I would say about more than 6
You need to pass with 25/30. If you get 6 wrong you fail.
30 questions. 6 wrong=fail
All of them - you'd fail, but the question did not say anything about passing the test!
You could fail seven questions, and still meet the minimum mark required.
http://dmvanswers.com/questions/297/How-many-questions-do-I-have-to-get-right-to-pass-drivers-permit-test
To pass the test you need 70% of the questions right.
5
You can get them all wrong. You won't pass the test, but that is not a requirement of the question.
20
If a test has 150 questions and you are aiming for a perfect score, you can get a maximum of 0 questions wrong. However, if you are allowed to get some questions wrong and still pass, it depends on the passing criteria set by the test administrator. For example, if the passing score is 70%, you can get up to 45 questions wrong (150 questions * 30% incorrect = 45 questions).
no more than 7
37 questions wrong gives you a 70.2% correct.