A shared grandfather — Blood Relations Aptitude Question
A shared grandfather: A's mother's father is B's father. How is A related to B? Answer and worked solution on CodeKairo.
- Topic: Blood Relations
- Section: Logical Reasoning
- Difficulty: Hard
- Time target: 105 seconds
Question
A's mother's father is B's father. How is A related to B?
Options
- Son or daughter
- Nephew or niece
- Brother or sister
- Cousin
Show the answer and the worked solution
Correct answer: B. Nephew or niece
Worked solution
- A's mother's father is A's maternal grandfather.
- He is also B's father, so A's mother and B are brother and sister.
- A is therefore the child of B's sibling — B's nephew or niece.
Answer: Nephew or niece.
The idea
When two chains meet at one person, the people either side of them are siblings. From there the answer is one more generation down.
Shortcut. Two people with the same father are siblings, so A's mother and B are siblings; a sibling's child is a nephew or niece.
Common trap. "Brother or sister" — dropping 'mother's' and reading 'A's father is B's father', which would make A and B siblings.