Answer
511
Work Step by Step
Since there is an even number, there is no single median, but a two middle numbers (these numbers are given). To find the median you take the average of these numbers
$(513+509)/2=511$
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.