Answer:
Not necessary
Step-by-step explanation:
Given that the median score for a test was 78%. Your professor announced that anyone with a score below the median would have to retake the test. Your score was in the 65th percentile.
Since your score is in the 65th percentile, this implies that 65% of students got scores below you.
Only if you are in 50th percentile you are in median, and if your score is below 50th percentile, you will be below median.
In that case only, you have to retake the test
Here since you are in 65th percentile, you are very much above the median
and hence need not retake the test