Decode, check, and know when to stop
The last lesson puts the routine together for coded and family questions: decode only what the question needs, check the answer with lessons 12 and 13, and stop as soon as the answer is complete. You also see what the exam's marking (+2 for a right answer, −0.50 for a wrong one) means for a question you have only narrowed down.
Guess first
In a code, A @ B means "A is the son of B", A # B means "A is the sister of B" and A & B means "A is the mother of B". If P @ Q # R & S, how is P related to S?
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Correct answer: A
P @ Q: P is Q's son. Q # R: Q is R's sister. R & S: R is S's mother. So P is the son of the sister of S's mother: S's cousin, मौसेरा भाई. Every gender the answer needs is given: P is a son, Q a sister, R a mother.
Option B: P and S have different mothers, who are sisters: they are cousins.
Option C: P is R's nephew (her sister's son). The question asks about S, one rung below R.
Option D: Nothing the answer needs is missing.
Hint: Decode the three pairs, then walk from S.
Decode, name, check, and the answer is there. The rest of this lesson is about doing exactly that much, and not more.
Decode, check, stop
Solving a coded question is like a short train journey.
Boarding decoding
turn only the pairs on your route into sentences
The journey the path
from the person after "related to" to the other one
The ticket check the checks
direction, gender, side, readings (lessons 12 and 13)
Getting off stopping
once the answer is complete, the remaining pairs do not matter
This lesson uses this key:
| Symbol | Meaning |
|---|---|
| A @ B | A is the son of B |
| A # B | A is the sister of B |
| A & B | A is the mother of B |
A pair you have not decoded cannot mislead you. A pair you do not need is only time.
See it: when to stop decoding
Take M # N & O @ P, and the question "How is M related to O?"
Decode, check, stop:
- Question line: M to O.
- Decode from the pairs that hold M and O: M # N (M is N's sister), N & O (N is O's mother).
- Name: M is the sister of O's mother: O's maternal aunt, मौसी.
- Check: M is a woman (a sister); the side comes from O's mother. Nothing is missing.
- Stop: O @ P only says who P is. It cannot change M's relation to O.
flowchart TD M["M: sister of N"] --- N["N: mother of O"] N --> O["O"]
Try it on paper. Write a four-pair expression in this key. Ask yourself a question about two of its names, and circle only the pairs you need.
Find the rule
Using this lesson's key, to find how X is related to Y in X @ Y # Z & W, which pairs do you need to decode?
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Correct answer: A
X @ Y alone says X is Y's son. That is the whole answer, gender included. The other pairs are about Z and W.
Option B: Y # Z adds Y's sibling, who is not on the path.
Option C: Decoding everything gives the same answer, more slowly.
Option D: Without the first pair, nothing links X to anyone.
Hint: Which pair holds both X and Y?
Using this lesson's key, from P & Q @ R, which statement is certain?
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Correct answer: A
P & Q: P is Q's mother. Q @ R: Q is R's son, so Q is a man. So Q is P's son.
Option B: R stands only on the right of a symbol, so R's gender is not given: R is Q's parent.
Option C: @ makes Q a son, not a daughter.
Option D: & makes P Q's mother, not his sister.
Hint: For each statement, find the pair it needs and the gender it needs.
Name the rule
Decode what you need, check it, then stop.
- Read the question line first (lesson 13).
- Decode only the pairs on the path between the two people, plus any pair that gives a gender the answer needs.
- Name the relation and run the checks: direction, gender, side, readings (lesson 12).
- Stop. Remaining pairs and clues cannot change the answer.
- If a question has gone on far longer than the rest, narrow it down, answer or leave it, and move on.
A right answer gets +2 and a wrong one −0.50 (notice, §13.8.2). If you have ruled out two options and one of the remaining two is right, answering is worth (2 − 0.50) ÷ 2 = +0.75 marks on average. A pick among all four with nothing ruled out is worth (2 − 3 × 0.50) ÷ 4 = +0.125. Ruling options out, with the traps from these lessons, is what makes an answer worth giving.
Worked, half-done, solo
Question
Using this lesson's key, if M # N & O @ P, how is M related to O?
Solution
- Question line
M to O, one relation.
- Decode the pairs on the path
M # N: M is N's sister. N & O: N is O's mother.
- Name it
M is the sister of O's mother: O's maternal aunt, मौसी.
- Check
M is a woman (a sister); O's link runs through his or her mother; one reading only.
- Stop
O @ P says only that O is P's son. It changes nothing.
Answer: M is O's maternal aunt, मौसी.
Watch out: The last pair does tell O's gender (a son), but the question is M to O, so O's gender is not needed.
Now finish one that is half done.
Using this lesson's key, if W & X # Y @ Z, how is Y related to W? Decode: W is X's mother. X is Y's sister, so W is Y's mother too. Y @ Z: Y is Z's son, so Y is a man. Here the last pair is needed: it gives Y's gender. So Y is W's ...
Show answer
Correct answer: A
W is Y's mother, and Y is a man: Y is W's son.
Option B: @ makes Y a son, a man.
Option C: That adds a rung: Y is W's child, not her grandchild.
Option D: Mother is W as seen from Y: the reverse question.
Hint: Which pair gives Y's gender?
And one on your own.
Using this lesson's key, if K @ L # M & N, how is N related to K?
Show answer
Correct answer: A
K @ L: K is L's son. L # M: L is M's sister. M & N: M is N's mother. So N is the child of the sister of K's mother: K's cousin. N's gender is never given: मौसेरा भाई या बहन.
Option B: "Son" needs N to be a man; N stands only on the right of a symbol.
Option C: K and N have different mothers, who are sisters: they are cousins.
Option D: N is the child of L's sister: that is N's relation to L. The question asks about K, one rung below L.
Hint: Decode all three pairs, then check whose gender is given.
The traps
- Decoding everything: decode the path, and a gender pair only if the answer needs it.
- Stopping too early: a pair that gives a needed gender is part of the path.
- "Cannot be determined" for a missing detail the answer does not need: "sister's child" is exact without the child's gender.
- Drifting: a question far slower than the rest uses the time of the quick ones.
- Answering with nothing ruled out: narrow the options first; that is what makes an answer worth giving.
Using this lesson's key, if G # H & I, how is I related to G? Seema answered "Cannot be determined", because I's gender is not given. What went wrong?
Show answer
Correct answer: A
G # H: G is H's sister. H & I: H is I's mother. So I is the child of G's sister: G's sister's child, भांजा या भांजी. I's gender changes only the word for I, not the relation.
Option B: Read backwards, H would be G's sister; Seema gave no relation from that reading.
Option C: The reverse would be G to I: maternal aunt. Seema gave no relation at all.
Option D: "Sister's child" is certain in every reading.
Hint: Which missing detail would change the relation itself?
Mixed check
Lalita is the maternal aunt of Aman, a boy. How is Aman related to Lalita?
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Correct answer: A
Lalita is the sister of Aman's mother. Walk back from Lalita: across to her sister (Aman's mother), down to her son Aman. Aman is Lalita's sister's son: her भांजा.
Option B: The person in the middle is Lalita's sister, not her brother.
Option C: That repeats the clue: Lalita to Aman.
Option D: Aman is the son of Lalita's sister, not of Lalita.
Hint: Lesson 14: walk back from Lalita.
(1) A is the father of B and C. (2) B is married to D. (3) E is the son of B and D. (4) F is E's wife, and G is the daughter of E and F. How many generations are there in the family?
Show answer
Correct answer: A
Rows: A; then B, C and D; then E and F; then G. Four rows: four generations.
Option B: Three is the number of steps from the top row to the bottom row.
Option C: D and F married in; each sits on the partner's row, not on a new one.
Option D: Every person can be placed on a row.
Hint: Lesson 11: draw the rows and count them.
Quick reference
Decode, check, stop
- Decode
- only the pairs on the path, plus a pair that gives a needed gender the rest is time
- Check
- direction, gender, side, readings lessons 12 and 13
- Stop
- once the answer is complete remaining pairs cannot change it
- Marking
- +2 right, −0.50 wrong (notice, §13.8.2) narrowed to two: +0.75 on average; blind among four: +0.125
- Time
- 36 seconds a question on average in Part A a slow question uses the time of quick ones
Why it works: a coded question is an ordinary family question in disguise. Decoding only the path keeps it short, the checks keep it right, and stopping keeps the time for the next question.
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