In a certain code language, A # B means A is the sister of B. A @ B means A is the son of B. A & B means A is the wife of B. A % B means A is the father of B. How is Q related to R if P & Q % L # R & K?

Correct — C.

Rule: read the chain one symbol at a time, left to right, and write down the gender each symbol fixes.

P & Q: P is the wife of Q, so Q is male.
Q % L: Q is the father of L.
L # R: L is the sister of R, so L and R are siblings.
R & K: R is the wife of K.

Q is the father of L, and R is L's sibling, so Q is R's father too — Father, option (c).

Why the others are wrong

• (a)
  Sister — Sister would need Q to be female and a sibling of R. P & Q makes P the wife of Q, so Q is male, and Q % L makes him a parent rather than a sibling.
• (b)
  Mother — The generation is right but the gender is wrong. A mother is female, and P & Q fixes Q as P's husband, so Q is R's father.
• (d)
  Wife — P is the wife of Q, not Q of anyone. Q stands on the father side of the % symbol, one generation above R.

Coded blood-relation chains are read strictly left to right, one link at a time, and the gender clues carry as much weight as the links themselves.

Two symbols fix a gender here. & makes the letter on its left female (A is the wife of B), and % makes the letter on its left male (A is the father of B). # marks the left letter as a sister, so she is female as well.

Siblings share parents. Once L is R's sister, anything true of L's father is true of R's father.

Key facts

• In this code A & B means A is the wife of B, so the letter before & is female.
• A % B means A is the father of B, so the letter before % is male.
• A # B means A is the sister of B, which makes A and B siblings.
• A parent of one sibling is a parent of the other.

Common traps

• Reading & as husband rather than wife, which flips every gender in the chain
• Answering Mother because the parent link is seen but the gender clue is skipped
• Treating L # R as a parent-child link rather than a sibling link

No directly related past PYQ was found.