Hello everyone,

I cannot seem to grasp the idea of how I have to use probability in this problem:

"In Oslo 18121 school children were tested for colour blindess. These are the results:
Male: 8324 not colour-blind, 725 colour-blind.
Female: ? not colour-blind, ? colour-blind.

Determine the number of colour-blind females if colour-blindness is caused by a monogene recessive X-chromosomal gene."

This is the prerequisite genetics knowledge: This is a monohybrid crossing, which means that we regard only one characteristic. Mendel's laws state that when genotypes Aa x Aa are crossed, we get these combinations: AA, Aa, aA (also written as Aa) and aa.

Now my work so far:
Males from the parent generation can have the X^AY (not colour-blind) or X^aY (colour-blind) genotype. Females have X^AX^A, X^AX^a or X^aX^a (colour-blind) genotypes. However, I don't know how I need to combine these possiblities with the results for the male decendants. Does anyone have an idea?

Thanks in advance,
Tom Koolen