Pointing towards a man, a woman said, "His mother is the only daughter of my…

2023

Pointing towards a man, a woman said, "His mother is the only daughter of my mother." How is the woman related to the man?

  1. A.

    Mother

  2. B.

    Grandmother

  3. C.

    Sister

  4. D.

    Daughter

Show answer & explanation

Correct answer: A

CONCEPT: In blood-relation puzzles, a phrase like "the only daughter of X" acts as a strict pointer: if X truly has just one daughter, that phrase can be replaced with the identity of whoever is already known to be X's sole daughter -- there is no ambiguity left to resolve.

  1. "My mother" refers to the speaker's (the woman's) own mother.

  2. The woman states that her mother has an "only daughter" -- meaning her mother has exactly one daughter, no more.

  3. The woman herself is a daughter of her mother, and since no second daughter is possible ("only"), that one daughter must be the woman herself.

  4. Substituting this identity into the sentence, "His mother is [my mother's only daughter]" becomes "His mother is [the woman speaking]."

  5. Therefore the woman speaking is directly related to the man as his mother.

CROSS-CHECK: Draw a family tree -- the woman's mother has exactly one daughter, who is the woman herself. The man's mother is defined as that one daughter. So the man's mother is the woman -- consistent, with no contradiction.

Explore the full course: Deloitte Nla