In Drosophila melanogaster white eyes w is an Xlinked recess

In Drosophila melanogaster, white eyes (w) is an X-linked recessive mutation. Normal eyes are red (W). At the autosomal wing shape locus, normal shaped wings (Vg) are dominant to vestigial wings (vg). The following cross was made:

XWXw Vgvg x XWY Vgvg

What proportion of the progeny from this cross will be females with red eyes and normal wings? Write your as a numerical value rounded properly to 4 decimal digits. Do not write the answer as a fraction or percentage.

Solution

For fruit flies ( Drosophila melanogaster), the sex is determined by the presence of both sex chromosomes, as well the number of autosomes. Since the question does not mention about the total number of autosomes, we shall assume that the ratio of sex chromosomes: autosomes is same, and that it follows normal patter of inheritance. We also know that in flies,
the genotype XX will specify a female, and
the genotype XY will specify a male.

Now the cross is made between two parents with the following genotypes -
X^WX^w Vgvg x X^WY Vgvg

Now, during segregation, the alleles will independently assort with each other

Parent 1 - X^WVg, X^Wvg, X^wVg and X^wvg
Parent 2 - X^WVg, X^Wvg, YVg and Yvg

Let us draw a punnet board to analyze the possible genotypes and phenotypes-

X^WX^wVgvg
Female,Red, Normal

Now,

Total Number of phenotypes = 16
Number of phenotypes that are Female, with Red Eyes and Normal Wings = 6

Therefore,

Proportion of progeny that are Female with Red eyes and Normal Wings = 6/16 = 0.3750