Link to the calculations?
What is the avg rating in chess

Check out the chess.com leaderboard. It will show you the average rating for any given time control. Of course, this will only apply to users on the site and does not provide accurate information to deduce the average rating of any chess player who does not play chess on chess.com.
Here are the average ratings for blitz, bullet, and rapid according to the leaderboard at the time of publishing this comment.
Average blitz rating: 622
Average bullet rating: 590
Average rapid rating: 617

The average values for time controls are really in the global stats
But this thread is about the average ratings for players of various age ranges

Check out the chess.com leaderboard. It will show you the average rating for any given time control. Of course, this will only apply to users on the site and does not provide accurate information to deduce the average rating of any chess player who does not play chess on chess.com.
Here are the average ratings for blitz, bullet, and rapid according to the leaderboard at the time of publishing this comment.
Average blitz rating: 622
Average bullet rating: 590
Average rapid rating: 617
Remember 1000 is beginner. Most people are worse than beginners.
Kids: 350 elo
Teen: 800 elo
Adult: 1000 elo depends