Huntington disease is a rare condition in humans, caused by a dominant allele of a single gene, and that results in a slow but inexorable deterioration of the nervous system. The probability that a person with the Huntington genotype will express the phenotype varies with age. Assume that 50% of those inheriting the HD allele will express the symptoms by age 40. Janelle is a 35-year-old woman whose father has Huntington disease. She currently shows no symptoms. What is the probability that Janelle will show symptoms in five years