I'm a fairly new sprinter. My PRs as of last year are as follows:
100 - 12.74
200 - 25.68
300 - 41.x
400 - 61.58 (I had no idea how to run the race and I didn't go out hard enough)
The season starts in March. After two weeks, my coach has us do a 300m time trial to see who would be good in some of the relays. He said that if you can get under 40 seconds, that could put you on the varsity 4x400. Most of the people on my team think I can do it if I do some off-season training.