That's the problem when you have mixed up batches of chick's. You don't know what they are until later. I got tired of that route, so that's why I have these Bielefelder's now. I can tell what sex that they are as soon as they hatch.I have a chest freezer. I just started it up (early) so there's room.
Edit: probably more than 4 cockerels out of the 13 straight run hatchery surprise. I'm thinking 4-6 pullets but was just going by feathering speed and growth speed, thickness of legs and pink/larger combs. But with all possibly different breeds not a lot for comparison, just "my what a big pink comb for 4 weeks!"