In a certain code language, ‘A + B’ means ‘A is the mother of B’; ‘A − B’ means ‘A is the brother of B’; ‘A × B’ means ‘A is the wife of B’ and ‘A ÷ B’ means ‘A is the father of B’. Based on the above, how is 4 related to 1 if ‘4 × 3 − 2 − 1’?

Correct — B. Substitute one symbol at a time, left to right.

Rule: 4 × 3 makes 4 the wife of 3.

3 − 2 makes 3 the brother of 2, and 2 − 1 makes 2 the brother of 1.

So 3, 2 and 1 are siblings and 3 is male, which makes 3 a brother of 1 as well.

4 married into that set of siblings, so 4 is 1's brother's wife — option (b).

Why the others are wrong

• (a)
  Sister — 4 enters the chain only through ×, the marriage symbol. A sister would need 4 to share a parent with 1, and nothing in '4 × 3 − 2 − 1' gives 4 a blood link to anyone.
• (c)
  Father’s sister — This needs 4 to be a sibling of 1's father, but the father symbol ÷ never appears in the string. 3 is a brother of 1, not a parent of 1.
• (d)
  Mother — The mother symbol + does not occur in '4 × 3 − 2 − 1' at all. 4 is attached to 3 by ×, which fixes her as a wife, never as a parent.

Symbol-relation items hand you four operators and a chain, and the whole task is patient left-to-right substitution.

Two habits decide the mark. First, let each symbol fix gender — wife makes 4 female, brother makes 3 and 2 male.

Second, treat sibling links as transitive: 3 is the brother of 2 and 2 is the brother of 1, so 3 is a brother of 1.

Only then read off what 4 is to 1, which here is a relation by marriage rather than by blood.

Key facts

• 'A × B' means A is the wife of B, so the left-hand person in a × is female.
• 'A − B' means A is the brother of B, so the left-hand person in a − is male.
• Sibling links chain: 3 brother of 2 and 2 brother of 1 makes 3 a brother of 1.
• A brother's wife is a sister-in-law, a relation created by marriage.

Common traps

• Reading the chain right to left, which attaches 4 to the wrong person.
• Assuming 1 is male because 2 and 3 are, when the chain never says so.
• Forgetting that only + and ÷ create a parent link, so a chain without them cannot produce a mother or a father.

No directly related past PYQ was found.