What are the phenotypes for yy, yy, yy. where yellow (y) hair is dominant to blue (y)?

Well simply knowing that yellow hair colour is dominant to blue, Yellow Y hair allele will produce the functioning protein or pigment to product the yellow colour whereas the blue colour is only produced if both recessive alleles are present.

YY = yellow
Yy = Yellow
yy = blue

Black becasue your dream isnt develpoped