Awoman heterozygous for color blindness (an x-linked recessive allele) marries a man with normal color vision. what is the probability that their first child will be color blind?

There are a 50 - 50 percent chances that the first child will be color blind if a woman who's heterozygous for color blindness with an x-linked recessive allele marries a man with a normal color vision. It is known that Colorblindness is an X-linked trait in humans.