The expected ratio of hens to roosters is supposed to be 50:50 when hatching. It's funny though, just about everyone I know who hatches eggs gets a higher percentage of roosters without fail - usually about 65-70% roosters. I'll have to ask my daughter how her last few batches have turned out ratio wise.
When I was a boy growing up we let our chickens hatch eggs a few times. The expected ratio usually turned out to be out 10% surviving and 90% dog killed. We had a bird dog (weimaraner). He could care less about the adult chickens but he went nuts for the baby chicks, guess he didn't see them as chickens at that stage. He'd grab one and carry it proudly around for about 5 minutes until he couldn't take the excitement and would bite down too hard. There was usually no getting them away from him either. Good looking dog, but a lousy hunter and one of the most hardheaded dogs I've ever known.