We simply want to know what is the probability that he or she is colorblind? Well, out of these four cases, two of these cases produce a colorblind individual. So case number one, this colorblind female, and case number two, this color blind male. Both of these cases are normal. So that means two out of four children or two out of four cases produce a color blind individual. And we know that two out of four is the same thing as 0.5.