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Sequences and Series MCQs

Class 11 Maths — questions with answers and worked explanations.

20 free questions Class 11 Maths Answers + explanations No sign-up

These questions are drawn from the Pariksha Sutra question bank for Sequences and Series, part of the Class 11 Maths syllabus. Each one shows the correct answer and, where a method helps, the working behind it.

Read the question, decide your answer before looking, then check the explanation — that is what turns practice into marks. If a question catches you out, the explanation is the part worth re-reading.

Questions

Question 1
If the nth term of a sequence is a_n = n^2 + 1, then the 4th term is:
  1. 15
  2. 18
  3. 16
  4. 17
Answer: 17
Question 2
The number of terms in the AP 7, 13, 19, ..., 205 is:
  1. 35
  2. 34
  3. 32
  4. 33
Answer: 34
Question 3
The sum of the first n even numbers 2 + 4 + 6 + ... equals:
  1. n(n+1)
  2. n^2
  3. 2n
  4. n(n+1)/2
Answer: n(n+1)
Question 4
The arithmetic mean of the first n natural numbers is:
  1. (n+1)/2
  2. n(n+1)/2
  3. n/2
  4. (n-1)/2
Answer: (n+1)/2
Question 5
The sum of the GP 1 + 2 + 4 + ... up to 10 terms is:
  1. 1023
  2. 2047
  3. 1000
  4. 511
Answer: 1023
Question 6
The sum of the first n odd numbers 1 + 3 + 5 + ... + (2n-1) equals:
  1. n(n+1)/2
  2. n^2
  3. n(n+1)
  4. 2n
Answer: n^2
Question 7
If a, b, c are in GP, then which relation holds?
  1. b^2 = a + c
  2. b^2 = ac
  3. 2b = a + c
  4. b = a + c
Answer: b^2 = ac
Question 8
If the nth term of an AP is 3n - 1, its common difference is:
  1. 2
  2. -1
  3. 3
  4. 1
Answer: 3
Question 9
For the AP 3, 7, 11, ..., the 20th term is:
  1. 77
  2. 75
  3. 83
  4. 79
Answer: 79
Question 10
If 5, x, 17 are in AP, then x equals:
  1. 10
  2. 12
  3. 9
  4. 11
Answer: 11
Question 11
In an AP with common difference 4, the value of a_10 - a_6 is:
  1. 20
  2. 16
  3. 12
  4. 8
Answer: 16
Question 12
The value of 51 + 52 + 53 + ... + 100 is:
  1. 3675
  2. 3750
  3. 3800
  4. 3775
Answer: 3775
Question 13
The arithmetic mean of 8 and 20 is:
  1. 14
  2. 16
  3. 12
  4. 13
Answer: 14
Question 14
The geometric mean inserted between 3 and 27 is:
  1. 18
  2. 9
  3. 6
  4. 12
Answer: 9
Question 15
In a GP the 7th term is 8 times the 4th term. The common ratio is:
  1. 4
  2. 8
  3. 3
  4. 2
Answer: 2
Question 16
The common ratio of an infinite GP with first term 5 and sum 15 is:
  1. 1/2
  2. 3/4
  3. 2/3
  4. 1/3
Answer: 2/3
Question 17
For the GP 2, 6, 18, ..., the 5th term is:
  1. 162
  2. 108
  3. 54
  4. 486
Answer: 162
Question 18
The sum of the infinite GP 1 + 1/2 + 1/4 + ... is:
  1. 2
  2. 3/2
  3. 1
  4. 4
Answer: 2
Question 19
The sum of the series 2 + 4 + 6 + ... + 100 is:
  1. 2550
  2. 2600
  3. 2450
  4. 2500
Answer: 2550
Question 20
If three arithmetic means are inserted between 1 and 9, the second mean is:
  1. 3
  2. 6
  3. 4
  4. 5
Answer: 5

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