Final answer:
A researcher should check an average of 12 men to find one who is colorblind, due to the prevalence of the X-linked recessive disorder being approximately 1 in 20 males, contrasted with 1 in 400 females.
Step-by-step explanation:
On average, a researcher should expect to check about 12 men to find one who is colorblind. This is because color blindness is an X-linked recessive disorder, which means it is more common in males than females due to the differences in sex chromosomes. With the statistical occurrence of color blindness affecting approximately 1 in 20 males, it can be inferred that approximately one out of every 20 men will exhibit color blindness.
The reason for this discrepancy is tied to the fact that males have one X chromosome and one Y chromosome, while females have two X chromosomes. A male with the colorblind trait on his X chromosome does not have another X chromosome to potentially counter that trait, resulting in the expression of color blindness. In contrast, a female would have to inherit the trait from both parents to express the condition due to having two X chromosomes. As information provided by Birch (2012) indicates, roughly 8% of males of European Caucasian descent and lesser percentages in other ethnic groups have red-green color deficiency, whereas only about 0.4% of females from European Caucasian descent exhibit the trait. Given this data, we can assume an average ratio when screening a diverse population.