Chapter 4: Sequences and Series – MCQs Test (Class 11, Federal Board)

This MCQs test is designed to help Class 11 students grasp the core concepts of Sequences and Series from the National Book Foundation syllabus (Federal Board). It covers arithmetic and geometric sequences, sum formulas, infinite series, and real-world applications—all essential topics for your board exams!

Chapter 4: Sequence and Series | National Book Foundation

April 15, 2026

1. 
A sequence $a_{n}$ is an arithmetic sequence if $\forall \, n\in\,\mathbb{N}$ and $n>1$:

2. 
In the sequence $1,2,2,3,3,3,4,4,4,4,...$ where n-consecutive terms have the value n, the $22^{nd}$ term is:

3. 
Predict the general term for the sequence $\frac{4}{3},\frac{4}{9},\frac{4}{27},\frac{4}{81},...$

4. 
If $a,b,c$ are in A.P, then $3^{a},3^{b},3^{c}$ are in:

5. 
$a_{5}$ in G.P $3,6,12,...$ will be _____

6. 
G.Ms between $1$ and $\frac{1}{3}$ is:

7. 
Sum of the series $1+3+5+7+9+11+...+n$ terms is:

8. 
For what value of $n$, $\frac{a^n+b^n}{a^{n-1}+b^{n-1}}$ is the A.M between a and b?

9. 
If $a_{n}-a_{n-1}=n+2$, $a_{1}=2$ then $a_{3}=?$

10. 
Let $a,b$ be two positive numbers, where $a>b$ and $4\times\,G.M=5\times\,H.M$ for the numbers, the a is:

11. 
If $\frac{1}{a},\frac{1}{b}$ and $\frac{1}{c}$ are in A.P then common difference is equal to_________.

12. 
An infinite sequence has no __________

13. 
The nth term of an A.P with usual notions is ______

14. 
If $a_{n-2}=3n-11$ then nth term is

15. 
If $x,y,z$ are in H.P. Sequence then value of z is ______

16. 
The formula $S_{n}=\frac{a(r^{n}-1)}{r-1}$ is used for sum of a terms of G.P. if ____

17. 
$\sum_{k=1}^{n} k=?$ or (sum of first n terms)

18. 
The general term of the given series $\frac{1}{1.3}+\frac{1}{2.5}+\frac{1}{3.7}+...$ is

19. 
If $y=\frac{2}{3}x+\frac{4}{9}x^2+\frac{8}{27}x^3+....$ then interval of convergence is____

20. 
$\sum_{k=1}^{10} 3=?$

21. 
For an infinite geometric series for which $|r|

22. 
Sum of $n$ terms of an A.P is ____

23. 
In $\frac{1}{4.7}+\frac{1}{7.10}+\frac{1}{10.13}+$...., then $n^{th}$ term is:

24. 
$\sum_{k=1}^{n} 5$ is equal to:

25. 
Find first term of the geometric series, when $S_{n}=30,n=4,r=-2$

26. 
If $\frac{4}{7}$ be the third term of H.P, then third term of A.P is:

27. 
Geometric mean of Two positive numbers a and b

28. 
The A.M between two numbers a and b is ________

29. 
If $a,b,c$ are in G.P and $a>0,b>0,c>0,$ then the reciprocals of $a,b,c$ form ______

30. 
The next term of G.P. $1,2,4,8,16,...$ is:

31. 
The arithmetic mean in the sequence $-7$,_,_,$5$ are

32. 
The $(n+1)th$ term of an A.P is _______

33. 
What is sum of n term with nth term $a_{n} = 4n+1$

34. 
$\sum_{k=1}^{n} k^{2}=?$ or $(1^2+2^2+3^2+...+n^2)=?$

35. 
An infinite geometric series is convergent if _____

36. 
A.M between $\frac{a}{2}$ and $\frac{2}{a}$ is

37. 
If $\frac{1}{a},\frac{1}{b}$ and $\frac{1}{c}$ are in G.P then common ratio is equal to_________

38. 
Sequence is denoted by______

39. 
$\frac{1}{k}, \frac{1}{2k+1}, \frac{1}{4k-1}$ are in H.P then $k=?$

40. 
Find the $26^{th}$ terms from the end of A.P : $2,7,12,17,...,222.$

41. 
Sum of $n$ arithmetic means between a and b is ________

42. 
Which term of $64,60,56,52,...$ is zero?

43. 
$\sum_{k=1}^{n} 1=?$

44. 
$0.1+0.01+0.001+0.0001+....$ the sum is:

45. 
$a_{n}=\frac{(-1)^{n+1}}{2^{n}}$, then $a_{6}=?$

46. 
If $a,A,b$ are in A.P then $2A=?$

47. 
The series $1+\frac{x}{2}+\frac{x^2}{4}+...$ is convergent if________

48. 
$\sum_{k=1}^{n} k^{3}=?$ or $(1^3+2^3+3^3+...+n^3)=?$

49. 
$S_{n}=1+2+3+...+n$ can also be shown as_______

50. 
The sigma notation for the sum $-2+4-6+8$ is:

51. 
Arithmetic Mean between two numbers $\frac{1}{a}$ and $\frac{1}{b}$ is:

52. 
In geometric sequence nth term equal to

53. 
If the nth term of an A.P is $\frac{1}{2}(3-n)$ then first three terms are _________

54. 
If $a_{1}$ and $r$ are the first term and common ratio respectively then the $(n+1)^{th}$ term of G.P is________

55. 
The reciprocal of the term of H.P is.....

56. 
If $\frac{1}{a},\frac{1}{b}$ and $\frac{1}{c}$ are in A.P then b is equal to_________.

57. 
The sum $\sum_{r=2}^{\infty} \frac{1}{r^2-1}$ represents:

58. 
$\sum_{k=1}^{3} k^2$ is equal to:

59. 
Sum of the series $\frac{5}{(13)^{1}}+\frac{55}{(13)^{2}}+\frac{555}{(13)^{3}}+\frac{5555}{(13)^{4}}+...$ up to $\infty$ is:

60. 
If $a,b$ are negative and G.M is also negative

61. 
The nth term of sequence $\frac{1}{3},\frac{2}{5},\frac{3}{7},....$ is:

62. 
$\sum_{j=1}^{10} \sum_{i=1}^{15} k =?$

63. 
How many terms of sequence $18,15,12,....$ are needed to give a sum of 63?

64. 
If A,G,H have their usual meanings and 'a' and 'b' are positive distinct real numbers and $G>0$, then:

65. 
The $10^{th}$ term of $\frac{1}{2},\frac{1}{5},\frac{1}{8},...,$ is:

66. 
Arithmetic mean between $2+\sqrt{2}$ and $2-\sqrt{2}$ is:

67. 
What is the sum of infinite G.P; $2,\sqrt{2},1,...?$

68. 
An arithmetic progression has a first term 12 and a fifth term 18, then the sum of first 25 term is.

69. 
If $\frac{1}{5}, \frac{1}{8}$ are two H.M between $\frac{1}{2}$ and $b$ then be equals to

70. 
An arithmetic series $S_{n}$ equals to ____

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