In a coding system, ‘PROJECT’ is written as ‘CEOPRT’ and ‘PLANE’ is written as ‘ELNP’. Then, in the same coding system the ‘ORGANISED’ will be written as :
- (1)ADEGIOSR
- (2)ADEGIROS
- (3)ADEGOIRS
- (4)ADEGIORS
Answer
Why
Correct — option (4), ADEGIORS.
Find the rule from the first example.
PROJECT has 7 letters: P, R, O, J, E, C, T. The code CEOPRT has 6.
The missing letter is J, the 4th letter: the middle of 7.
The other six in alphabetical order: C, E, O, P, R, T = CEOPRT.
Check it on the second example.
PLANE has 5 letters: P, L, A, N, E. The code ELNP has 4.
The missing letter is A, the 3rd letter: the middle of 5.
The other four in alphabetical order: E, L, N, P = ELNP.
Rule: drop the middle letter, then write the remaining letters in alphabetical order.
Apply it to ORGANISED: O, R, G, A, N, I, S, E, D (9 letters).
Middle letter: the 5th, N. Drop it.
Remaining: O, R, G, A, I, S, E, D.
Alphabetical order: A, D, E, G, I, O, R, S = ADEGIORS.
The idea to remember: a rule is found only when it fits every example given — here, the middle letter goes and the rest are sorted.
Why the others are wrong
- (1)ADEGIOSR — Option (1) has the right eight letters, with N dropped, and is in order up to O. It then puts S before R.
R is the 18th letter and S the 19th, so in alphabetical order R comes before S. The ending must be R, S, as in ADEGIORS.
- (2)ADEGIROS — Option (2) has the right letters but puts R before O.
O is the 15th letter and R the 18th, so O must come before R. After I, the alphabetical order is O, R, S, which gives ADEGIORS.
- (3)ADEGOIRS — Option (3) has the right letters but puts O before I.
I is the 9th letter and O the 15th, so I must come before O. The order after G is I, O, R, S, which gives ADEGIORS.
Concept
Coding-decoding asks you to infer a rule from one or more word–code pairs and apply it to a new word. A rule can shift each letter forward or back, reverse the word or part of it, swap positions, drop letters, or sort letters.
Working method: compare lengths first. A code shorter than its word means letters were dropped, so find which ones and what they share. Then check whether the kept letters moved or changed.
A rule counts only when it produces every given code exactly. Testing on the second example is what separates the rule from a lucky guess.
RPSC's 2024 syllabus lists "Coding/Decoding" under Mental Ability in Reasoning & Mental Ability.
Letter codes rest on the order of the alphabet. Fixed anchors help: E, J, O, T and Y are the 5th, 10th, 15th, 20th and 25th letters, so the position of any letter can be found by counting on or back from the nearest one.
Sorting letters into alphabetical order is the same operation a dictionary uses on whole words; it depends only on each letter's position, not on how the word sounds.
Key facts
- Rule in this code: drop the middle letter of the word, then arrange the remaining letters alphabetically.
- PROJECT drops J (4th of 7) to give CEOPRT; PLANE drops A (3rd of 5) to give ELNP.
- ORGANISED has 9 letters; its 5th letter N is dropped and the rest sorted give ADEGIORS.
- Alphabet positions of the answer's letters: A 1, D 4, E 5, G 7, I 9, O 15, R 18, S 19.
- E, J, O, T and Y are the 5th, 10th, 15th, 20th and 25th letters of the English alphabet.
The same two steps turn PROJECT into CEOPRT and PLANE into ELNP.
Study next
Common traps
- "Sort the letters" alone fits neither example: PROJECT sorted is CEJOPRT, which keeps J, and PLANE sorted is AELNP, which keeps A.
- Identify the dropped letter by position, not by type. J is a consonant and A a vowel; what they share is being the middle letter.
- Options with the same letters differ only in order. Compare neighbouring letters by alphabet position; the first pair out of order rules an option out.
A question can give one or two word–code pairs and ask for the code of a new word, as this one does, or give a code and ask for the word. A question can use a rule that shifts letters, reverses all or part of the word, swaps positions, drops letters, or sorts them.
Related PYQs
UnlockIAS will link similar questions from RAS Pre 2023 and 2021 here once those papers are published on this site.
Practice
- practice — not a real PYQ
In a coding system, 'GARDEN' is written as 'ADEGNR' and 'CANDLE' is written as 'ACDELN'. In the same coding system, 'MOBILE' will be written as:
- (a)BEILMO
- (b)BEILOM
- (c)BIELMO
- (d)EBILMO
Answer(1) — The rule is to write all the letters in alphabetical order: GARDEN gives A, D, E, G, N, R and CANDLE gives A, C, D, E, L, N. MOBILE gives B, E, I, L, M, O. Option (2) puts O before M, option (3) puts I before E, and option (4) puts E before B. - practice — not a real PYQ
In a coding system, 'PLANT' is written as 'LNPT' and 'GRAPHIC' is written as 'ACGHIR'. In the same coding system, 'STUDENT' will be written as:
- (a)ENSTTU
- (b)DENSTTU
- (c)ENSTUT
- (d)ENTSTU
Answer(1) — PLANT drops its middle letter A and sorts L, N, P, T; GRAPHIC drops its middle letter P and sorts A, C, G, H, I, R. STUDENT (7 letters) drops its 4th letter D, and S, T, U, E, N, T sorted give E, N, S, T, T, U.Option (2) keeps D; option (3) puts U before the second T; option (4) puts T before S.