The sum of the first k terms of a series S is 3k2+5k. Which one of the following is correct?

The terms of S form an arithmetic progression with common difference 6.

The terms of S form an arithmetic progression with common difference 14.

The terms of S form a geometric progression with common ratio 10/7.

The terms of S form a geometric progression with common ratio 11/4.

Sequence And Series — NDA Previous Year Questions

63 solved PYQs · 2021–2025 · Mathematics

Solved PYQs: 63
Years covered: 2021–2025
Avg / year: ~13
Subject: Mathematics

How many NDA questions come from Sequence And Series?

Sequence And Series has contributed 63 questions to National Defence Academy Examination papers between 2021 and 2025 — an average of about 13 questions a year. That count is measured from EByAi’s bank of 15,695 NDA questions, not estimated from a syllabus. Every one of the 63 questions carries a written, step-by-step solution, and each is tagged to Sequence And Series within Mathematics, so you can drill this chapter across every year at once instead of hunting through paper PDFs. Practising a chapter’s full PYQ history is the fastest way to learn the patterns examiners reuse.

Sample Sequence And Series questions from real NDA papers

These are 5 real questions from the bank — exactly as asked, with the answer one tap away. All 63 Sequence And Series questions (with full written solutions) are available in practice.

Question 1 · NDA 2025
What is the harmonic mean of the numbers C(10,3), C(10,4), C(10,5), C(10,6) and C(10,7) ?
1. (A) $3150/19$
2. (B) $4000/19$
3. (C) $252$
4. (D) $225$
Show answerAnswer
$Answer: (A) 3150/19$
Question 2 · NDA 2025
How many terms of the series 1 + 3 + 5 + 7 +... amount to a sum equal to 12345678987654321?
1. (A) $11111111$
2. (B) $110000011$
3. (C) $111101111$
4. (D) $111111111$
Show answerAnswer
$Answer: (D) 111111111$
Question 3 · NDA 2025
The sum of the first k terms of a series S is 3k2+5k. Which one of the following is correct?
1. (A) $The terms of S form an arithmetic progression with common difference 14.$
2. (B) $The terms of S form an arithmetic progression with common difference 6.$
3. (C) $The terms of S form a geometric progression with common ratio 10/7.$
4. (D) $The terms of S form a geometric progression with common ratio 11/4.$
Show answerAnswer
$Answer: (B) The terms of S form an arithmetic progression with common difference 6.$
Question 4 · NDA 2025
How many terms are identical in the two APs 19, 21, 23,... up to 110 terms and 19, 22, 25, 28,... up to 75 terms?
1. (A) $35$
2. (B) $36$
3. (C) $37$
4. (D) $38$
Show answerAnswer
$Answer: (C) 37$
Question 5 · NDA 2025
If 5th, 7th and 13th terms of an AP are in GP, then what is the ratio of its first term to its common difference?
1. (A) $-3$
2. (B) $-2$
3. (C) $2$
4. (D) $3$
Show answerAnswer
$Answer: (A) -3$

Sequence And Series questions by year

Year	Questions	Share of chapter questions
2025	12
2024	11
2023	12
2022	14
2021	14

Practise these 63 questions with solutions

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FAQs

How many NDA questions have been asked from Sequence And Series?

EByAi's bank holds 63 real NDA questions from Sequence And Series, asked between 2021 and 2025 — about 13 per year on average. Every count is measured from actual papers, not estimated.

Is Sequence And Series important for NDA?

63 questions over 5 papers make Sequence And Series a steady-weightage chapter in NDA Mathematics. The year-wise table above shows exactly how often it appears.

Can I solve Sequence And Series PYQs online for free?

Yes. EByAi lets you solve NDA past-year questions in the browser with written solutions — free daily practice, no card needed.

More NDA Mathematics chapters

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