Is there a standard percentage of error when buying day old pullets?

[DottieMarie]

I have 15 pullets and once they arrived I kept thinking I will probably have at least 1 roo. I got used to the idea and now I really want one to be a boy but nothing stands out to me think so. They are 5.5 weeks so maybe I'll still get lucky.
Any guesses on percentage of error with 1 day olds?

 

[gritsar]

Most of the hatcheries I've checked out claim an error rate of 10%; or 90% of the time they get it right. Whichever way you want to look at it.