* School grades: Many schools average grades, so a 65+ on one test and a lower score on another would result in an average grade. Whether that average is passing or failing depends on the school's grading scale and the weight given to each test. Some schools might drop the lowest grade, or only consider the higher grade, depending on their policies.
* Medical tests: If these are medical tests, the meaning of the scores depends entirely on *what* is being tested. There's no general answer. A high score on one test and a low score on another could indicate a variety of things depending on the specific medical condition and tests involved. A doctor would interpret the results.
* Job performance evaluations: Similar to school grades, the impact depends on the company's policies. Some might average the scores, others might focus on the lowest score, and still others might look at both scores in conjunction with other factors.
* Entrance exams: Colleges and universities have specific admission requirements. A high score on one part of an exam might offset a lower score on another part, but only within the specific rules of that institution and admissions process.
To get a proper answer, you need to specify what kind of tests you're referring to.