Question 21
Three sisters discuss their ages.
Catherine: “I am 16 years old. I am younger than Stacy by 3 years. I am older than Fiona by 2 years.”
Stacy: “I am not the youngest. The difference between my age and Fiona’s age is 5 years. Fiona is 21 years old.”
Fiona: “I am younger than Catherine. Catherine is 18 years old. Stacy is younger than Catherine by 3 years.”
Exactly two sentences in each sister’s statement are true. How old is Stacy?
Answer format: enter one whole number without units. The source answer sheet uses four digits with leading zeros if needed; ordinary numeric entry is used here.
Catherine: “I am 16 years old. I am younger than Stacy by 3 years. I am older than Fiona by 2 years.”
Stacy: “I am not the youngest. The difference between my age and Fiona’s age is 5 years. Fiona is 21 years old.”
Fiona: “I am younger than Catherine. Catherine is 18 years old. Stacy is younger than Catherine by 3 years.”
Exactly two sentences in each sister’s statement are true. How old is Stacy?
Answer format: enter one whole number without units. The source answer sheet uses four digits with leading zeros if needed; ordinary numeric entry is used here.