Ah, chickens, what nightmares. I have them, this is easy.
Answer:
1).
BW + BW
B W
------------
B| BB| BW
W| BW| WW
(BB)Black: 25%
(BW)Speckled: 50%
(WW)White: 25%
2).
BW + WW
W W
-------------
B| BW| BW
W| WW| WW
(BW)Speckled: 50%
(WW)White: 50%
3).
BB +WW
B B
-------------
W| BW| BW
W| BW| BW
No, a black and white chicken cannot have a black chicken, as all the offspring would have the genotype BW, which would result in codominance. All offspring would be speckled.
I hope this helps :)
