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GATE 2020 EE GA Q.7: solution and answer

GATE 2020 · EEGA Q.7 · 2 marks · MCQ

Select the next element of the series: Z, WV, RQP, _

  1. (A)

    LKJI

  2. (B)

    JIHG

  3. (C)

    KJIH

  4. (D)

    NMLK

See the question in the paper
GATE 2020 EE GA question 7Tap to open full size

Answer and solution

ANSWER

The next element is KJIH, option (C).

Official answer: CSource: Official answer key, GATE 2020 EE (IIT Delhi)

  1. Write each letter's position in the alphabet (A = 1, ..., Z = 26): Z = 26; WV = 23, 22; RQP = 18, 17, 16.

  2. Group size: the terms have 1, 2 and 3 letters, so the next term has 4 letters. Inside each term the letters run backwards, one step at a time.

  3. Look at the letters skipped between one term and the next. Z to W skips Y, X (2 letters). V to R skips U, T, S (3 letters). The gap grows by 1 each time, so after P we skip 4 letters: O, N, M, L.

  4. So the next term starts at K (position 11). Check with the first letters: has differences , so the next difference is , and , which is K.

  5. Four letters counting down from K: K (11), J (10), I (9), H (8), giving KJIH.

  6. Check with the last letters: has differences , which is consistent. The other options break the rule: NMLK skips only O (1 letter), LKJI skips 3 letters (O, N, M) and JIHG skips 5. So the answer is (C) KJIH.

KEY IDEA

Two patterns run at once. Term length goes up by one (1, 2, 3, 4 letters, each term counting backwards), and the number of letters skipped between terms also goes up by one (2, 3, 4). So after P you skip O, N, M, L and start at K.

WATCH OUT FOR

Seeing only the four-letter length and picking the first backward run after P that looks right, such as NMLK (skips only O) or LKJI (skips O, N, M). Both miss the growing gap. Choosing JIHG means skipping one letter too many.

From the GATE 2020 EE paper. Every question of this paper · Download the full paper · All 41 Reasoning questions, with notes

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