To properly score a test by percentage, the educator should:

The correct answer is based on the fundamental method of calculating a percentage score. To properly score a test by percentage, the educator should divide the number of correct answers by the total number of questions on the test. This method provides a straightforward approach to determining how well a student performed relative to the entirety of the test.

For example, if a student answered 18 questions correctly out of a possible 20, the calculation would be 18 (correct answers) divided by 20 (total questions), which equals 0.90, or 90%. This reflects the student's performance as a percentage, which is a common practice in educational settings to provide clarity on a student's understanding and achievement.

The other choices do not accurately reflect this scoring method. Using an even number of questions might have its benefits in test design but does not influence how scores are calculated. Likewise, dividing the total number of questions by the number correct would yield an inverse relationship that doesn’t convey the student's performance accurately. And, while considering passing grades is important for educational fairness, it doesn’t pertain directly to the method of calculating a percentage score on a test.