AVERAGEIF on last N rows

This seems pretty simple but I can't find how to do it.

I keep a Google Sheet where I add several times a day new lines as following :

  | A     | B   | C   |  | ---   | --- | --- |1 | John  | 10  | 50  |2 | Peter | 20  | 70  | 3 | John  | 14  |     |4 | Peter | 12  | 82  |5 | John  | 5   | 55  |

I'm trying to get the average rating of the last N lines for a given name.That way I can send a report to "name" every now and then with an average of his N last ratings.