In a certain code language, ‘A + B’ means ‘A is the mother of B’; ‘A – B’ means ‘A is the husband of B’; ‘A × B’ means ‘A is the father of B’ and ‘A ÷ B’ means ‘A is the daughter of B’. Based on the above, how is K related to O if ‘K ÷ L − M + N × O’?
- (a)Sister’s daughter
- (b)Father’s sister
- (c)Mother’s sister
- (d)Father’s mother
Answer
Why
Correct — B. Decode the chain one symbol at a time, left to right.
K ÷ L → K is the daughter of L.
L − M → L is the husband of M.
M + N → M is the mother of N.
N × O → N is the father of O.
L and M are a married couple, so K and N are both their children — K a daughter, N a son. That makes K the sister of N.
N is O's father, so K is O's father's sister, option (b).
Why the others are wrong
- (a)Sister’s daughter — Sister's daughter puts K one generation below O. K is a child of L and M, the same generation as O's father N, so she stands above O, not below.
- (c)Mother’s sister — Mother's sister would need K to be a sibling of O's mother. The chain makes N — K's sibling — the father of O, because A × B means A is the father of B.
- (d)Father’s mother — Father's mother would make K the mother of N. K ÷ L makes K a daughter of L, so K and N are siblings, not parent and child.
Concept
Symbolic blood-relation questions are pure substitution. The symbols are redefined inside the question, so no meaning may be carried in from anywhere else.
Work left to right and write each link as a full sentence before you draw a tree. Two things settle most chains — each person's generation and their gender — and the legend fixes both.
Here − and × mark L and N as male, ÷ marks K as female and + marks M as female. O's gender is never fixed, and the question does not need it.
The answer describes K's relation to O, not O's relation to K. Reverse the direction and the correct paternal aunt becomes a niece, which is exactly what option (a) offers.
Key facts
- In this question's legend, A ÷ B means A is the daughter of B and A × B means A is the father of B.
- K and N are both children of L and M, which makes them brother and sister.
- N is O's father, so K is O's paternal aunt — the father's sister.
Study next
Common traps
- Reading the chain right to left, which inverts every generation in it.
- Giving a symbol the meaning it carried in some other question instead of the one printed here.
The redefine-the-symbol habit returns at 12 Sep 2024, 16:00, Reasoning Q.9, where + and − swap and × and ÷ swap before any arithmetic may be done.
Related PYQs
No directly related past PYQ was found.