BPSC 69th CCE Prelims General Studies · Question 148 of 144

Correct — A, 22187121812619. Build the rule from the two samples before touching the target word. In GREAT, three letters give their plain alphabet position: G is 7th, R is 18th, T is 20th, and the code opens 7, 18 and ends 20. The other two do not — E is the 5th letter but codes as 22, and A is the 1st but codes as 26. Both are vowels, and 22 = 27 − 5 while 26 = 27 − 1, which is the reverse position, the number a letter has when the alphabet is counted backwards from Z = 1 to A = 26. So the rule is: consonants take their forward position, vowels take 27 minus it, giving A = 26, E = 22, I = 18, O = 12, U = 6. MONK confirms it on a second sample — M 13, N 14 and K 11 are forward positions, and the vowel O, the 15th letter, codes as 27 − 15 = 12, producing 13121411 exactly. Now encode VIGOROUS letter by letter: V is a consonant, 22; I is a vowel, 18; G is a consonant, 7; O is a vowel, 12; R is a consonant, 18; O again, 12; U is a vowel, 6; S is a consonant, 19. Written out in order that is 22-18-7-12-18-12-6-19, and run together, 22187121812619 — option (a).

• (b)21177121811619 — Reads as 21-17-7-12-18-11-6-19, and it fails two checks at once. It opens with 21 when V, a consonant, must give its forward position of 22. Worse, its two O's come out as 12 and 11 — the same letter encoded two different ways in one word, which is impossible in any substitution code and can be spotted without computing anything else.
• (c)22187131813620 — The closest option, and the one that survives the quick checks longest: it opens correctly with 22-18-7 and keeps both O's identical. It fails on the actual counting — it gives O as 13 and S as 20, whereas O is the 15th letter so its reverse is 27 − 15 = 12, and S is the 19th letter so a consonant takes 19. It is the string produced by an alphabet miscount of one place in the middle of the sequence.
• (d)21187111711620 — Reads as 21-18-7-11-17-11-6-20. Like (b) it opens with 21 instead of 22, so V is already wrong before anything else is checked, and it then puts R at 17 rather than 18 and S at 20 rather than 19 — a whole run of consonants shifted one place. Any option whose first two digits are not 22 can be discarded on sight.

Coding-decoding items give one or more sample words with their codes and ask for the code of a new word. The families are few and worth recognising instantly: a fixed letter shift (each letter moves forward or backward by the same number of places), a positional code (each letter replaced by its number in the alphabet), a reversed-alphabet code (A becomes Z, B becomes Y, so a letter's value is 27 minus its position), symbol substitution (each letter maps to an arbitrary sign), and conditional codes in which the rule depends on the letter's class or on its place in the word. This question is the last kind — a single code with two rules inside it, one for consonants and one for vowels. The method never changes: tabulate every letter of every sample against its code, look for the letters that behave plainly, isolate the ones that do not, find what those exceptions have in common, and only then encode the target word.

Two working numbers make this fast. The forward positions A = 1 to Z = 26 must be instant, and so must the reverse row, which is easiest held as the single fact that forward plus reverse always equals 27 — so the reverse of E is 27 − 5 = 22 and the reverse of O is 27 − 15 = 12. The moment you see 22 sitting where E should be, that identity tells you what has been done. The second thing to notice is that the two samples together are generous: they cover the vowels E, A and O and six consonants, which is why a rule that reproduces both can be trusted rather than merely hoped for. From there the fastest route to the mark is elimination, not encoding. All four options are fourteen digits long, so length decides nothing — but the first letter does. V is a consonant and the 22nd letter, so any answer that does not begin 22 is dead, and that removes (b) and (d) at a glance. The last letter does the rest: S is a consonant and the 19th letter, so the code must end 19, which removes (c). One letter at each end of the word settles the question without encoding the middle at all. A third free check, useful when the ends are inconclusive, is that a repeated letter must repeat in the code — VIGOROUS has two O's, and option (b) gives them different values.

• The rule: consonants take their forward alphabet position (A = 1 … Z = 26) and vowels take the reverse position, 27 minus the forward position — so A = 26, E = 22, I = 18, O = 12, U = 6
• GREAT decodes as G 7, R 18, E 22, A 26, T 20 = 718222620, and MONK as M 13, O 12, N 14, K 11 = 13121411; the rule reproduces both samples exactly
• VIGOROUS = V 22, I 18, G 7, O 12, R 18, O 12, U 6, S 19 = 22187121812619
• Forward position plus reverse position always equals 27, which is the single identity that makes reversed-alphabet codes quick
• Elimination beats encoding here: V is the 22nd letter so the code must open 22, and S is the 19th so it must close 19; those two checks alone leave only one option standing

• Using 26 minus the position instead of 27 minus the position for the reverse — an off-by-one that corrupts every vowel in the answer
• Applying the vowel rule to consonants or the consonant rule to vowels once the word gets long
• Skipping the check that a repeated letter must produce identical digits — VIGOROUS has two O's, and one option gives them different values

BPSC puts at least one coding item in the reasoning block of every recent General Studies paper and rotates the target alphabet rather than the task — digits here in 2023, arbitrary symbols and a letter shift in the 2025 block — so the drill is always the same: rebuild the mapping from the samples, then apply it. UPSC keeps coding-decoding in CSAT Paper II under general mental ability, where it tends to appear as a shift or an arrangement rather than as a two-rule conditional code.

No directly related past PYQ was found.

• practice — not a real PYQ

  In the code language of the question above, in which consonants take their forward alphabet position and vowels take 27 minus their position, how will QUIZ be written?

  • (a)1761826
  • (b)17211826
  • (c)176181
  • (d)1061826

  Answer(a) 1761826 — Q is a consonant and the 17th letter, U a vowel giving 27 − 21 = 6, I a vowel giving 27 − 9 = 18, and Z a consonant and the 26th letter.

• practice — not a real PYQ

  In a certain code A is written as 26, E as 22 and G as 7. On the same rule, how will CUE be written?

  • (a)32122
  • (b)3622
  • (c)24622
  • (d)3621

  Answer(b) 3622 — the samples show consonants taking the forward position and vowels 27 minus it, so C is 3, U is 27 − 21 = 6 and E is 27 − 5 = 22.