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Not a summary of the answer. The actual working, the trap, the wrong options one by one, and what to do when the paper itself is broken.

Unit 6 · Coding-decoding · Jan 2025 · 08-01 Shift 2 · Q.18 Free sample
In a certain code, the following sentences have been coded as shown. What is the code for ‘walking’?
Arjun is walking to school  →  NA, SI, AG, DR, VI
Krishna is speaking to Arjun  →  KA, TK, DR, SI, NA
School is within walking distance of Krishna  →  VI, SI, NIH, AG, LE, KA, OP
1TK
2VIThe trap
3AGNTA key
4SI

The working

Start with what the intersections give. ‘Is’ appears in all three sentences and SI is the only code in all three, so is = SI. Sentences 2 and 3 share Krishna and is, with codes KA and SI, so Krishna = KA. Sentences 1 and 3 share three words — is, walking, school — and three codes: SI, AG and VI. Removing SI leaves AG and VI for walking and school. Reading each of those two sentences in order, the codes line up with the words as written, which puts walking at AG and school at VI.

⚑ This item is underdetermined — and here is why that matters

Set intersection alone does not settle this question. Walking and school occur in exactly the same two sentences and never apart, so no amount of intersecting can separate AG from VI — options 2 and 3 are both consistent with the substitution logic. The key resolves it by position, yet sentence 2’s codes are not in word order. So the paper applies its own rule selectively. In the hall: solve as far as the data allows, then take the keyed option — do not assume you have missed a step.

Why the other options fail

1TK appears only in sentence 2, so it codes ‘speaking’ — a word absent from the other two sentences.
2VI is a genuine candidate on the substitution logic alone, and is ruled out only by the positional reading above. It is the code for school.
4SI is the code common to all three sentences, so it belongs to ‘is’ — the only word common to all three.

Memory hook

When two words always travel together across every sentence, their codes cannot be separated by intersection. If the question still demands an answer, the paper is relying on code order — check whether the listed codes track the word order.

Start with the free topic. Decide after that.

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