Question

The a allele of a locus determining body size is a recessive,lethal and sex-linked trait. The a allele promotes a medium bodysize through incomplete dominance with the A allele. Individualswith the AA genotype have very large size. A separate autosomallocus exhibits recessive epistasis to the lethality of the a allele. At this autosomal locus, the B allele is dominant to the b alleleto determine a black coat color as opposed to a brown coat.If arabbit with a medium body size and black coat (heterozygous) ismated witha male with a very small body size and a brown coat, howmany offspring of 30 would have a very small body size?

My work:

Body size:

XAXA - > large

XAXa -> medium

XaXa - > very small

Coat Color:

BB - > black

Bb - > black

bb - > brown

Cross:

black coat (hetero) medium sized female x brown coat and verysmall male

XAXaBb x XaYbb

XAxa -> 0.25 Bb -> 0.50

xaxa -> 0.25 bb -> 0.50

xAy -> 0.25

XaY -> 0.25