To determine the fraction for the inheritance of Red green colorblindness the genotype of their parents must be considered although neither John nor Ann is color blind there is a very high probability that Ann will be a carrier if that is the case the fractions of the daughters of John and Ann that are expected to be carriers of that trait is 50% chance.
Explanation:
A punnet square can be used to determine any possible genotypic combinations in the parents. color blindness is a recessive X-linked trait in which the patient is not able to distinguish, red or green or blue color. The normal gene and its recessive allele are carried by X chromosome in men, this color blindness appears in the presence of a single recessive gene Whereas in women color blindness occur only when both chromosome carry the gene this shows criss cross inheritance
Colour blindness is recessive sex-linked traits, carried by the X chromosome that is manifested as the difficulty of an individual to distinguish different colours properly.
From the question above Ann doesn't have color blindness but her father does, thus there is a possibility that Ann is an heterozygous carrier of color blindness.
Therefore the chances of having a carrier for color blindness in a daughter is 25% or 1/4