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

July 14, 2026

Total Questions:  70

1. 
If $y=\frac{2}{3}x+\frac{4}{9}x^2+\frac{8}{27}x^3+....$ then interval of convergence is____

2. 
The formula $S_{n}=\frac{a(r^{n}-1)}{r-1}$ is used for sum of a terms of G.P. if ____

3. 
The A.M between two numbers a and b is ________

4. 
$\sum_{k=1}^{3} k^2$ is equal to:

5. 
Sequence is denoted by______

6. 
If $a,b,c$ are in A.P, then $3^{a},3^{b},3^{c}$ are in:

7. 
If $\frac{1}{a},\frac{1}{b}$ and $\frac{1}{c}$ are in A.P then b is equal to_________.

8. 
Find the $26^{th}$ terms from the end of A.P : $2,7,12,17,...,222.$

9. 
If A,G,H have their usual meanings and 'a' and 'b' are positive distinct real numbers and $G>0$, then:

10. 
$\sum_{k=1}^{n} k^{2}=?$ or $(1^2+2^2+3^2+...+n^2)=?$

11. 
The $10^{th}$ term of $\frac{1}{2},\frac{1}{5},\frac{1}{8},...,$ is:

12. 
The nth term of an A.P with usual notions is ______

13. 
If $a,b,c$ are in G.P and $a>0,b>0,c>0,$ then the reciprocals of $a,b,c$ form ______

14. 
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:

15. 
What is sum of n term with nth term $a_{n} = 4n+1$

16. 
For an infinite geometric series for which $|r|

17. 
Sum of the series $\frac{5}{(13)^{1}}+\frac{55}{(13)^{2}}+\frac{555}{(13)^{3}}+\frac{5555}{(13)^{4}}+...$ up to $\infty$ is:

18. 
In geometric sequence nth term equal to

19. 
Predict the general term for the sequence $\frac{4}{3},\frac{4}{9},\frac{4}{27},\frac{4}{81},...$

20. 
If $\frac{1}{a},\frac{1}{b}$ and $\frac{1}{c}$ are in A.P then common difference is equal to_________.

21. 
What is the sum of infinite G.P; $2,\sqrt{2},1,...?$

22. 
The sigma notation for the sum $-2+4-6+8$ is:

23. 
$\frac{1}{k}, \frac{1}{2k+1}, \frac{1}{4k-1}$ are in H.P then $k=?$

24. 
If $\frac{4}{7}$ be the third term of H.P, then third term of A.P is:

25. 
A.M between $\frac{a}{2}$ and $\frac{2}{a}$ is

26. 
$\sum_{j=1}^{10} \sum_{i=1}^{15} k =?$

27. 
$\sum_{k=1}^{n} k^{3}=?$ or $(1^3+2^3+3^3+...+n^3)=?$

28. 
$S_{n}=1+2+3+...+n$ can also be shown as_______

29. 
$0.1+0.01+0.001+0.0001+....$ the sum is:

30. 
The reciprocal of the term of H.P is.....

31. 
Sum of the series $1+3+5+7+9+11+...+n$ terms is:

32. 
G.Ms between $1$ and $\frac{1}{3}$ is:

33. 
If $\frac{1}{a},\frac{1}{b}$ and $\frac{1}{c}$ are in G.P then common ratio is equal to_________

34. 
Sum of $n$ terms of an A.P is ____

35. 
The $(n+1)th$ term of an A.P is _______

36. 
The nth term of sequence $\frac{1}{3},\frac{2}{5},\frac{3}{7},....$ is:

37. 
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:

38. 
The arithmetic mean in the sequence $-7$,_,_,$5$ are

39. 
If $x,y,z$ are in H.P. Sequence then value of z is ______

40. 
An infinite sequence has no __________

41. 
The general term of the given series $\frac{1}{1.3}+\frac{1}{2.5}+\frac{1}{3.7}+...$ is

42. 
Geometric mean of Two positive numbers a and b

43. 
A sequence $a_{n}$ is an arithmetic sequence if $\forall \, n\in\,\mathbb{N}$ and $n>1$:

44. 
In $\frac{1}{4.7}+\frac{1}{7.10}+\frac{1}{10.13}+$...., then $n^{th}$ term is:

45. 
If $a_{1}$ and $r$ are the first term and common ratio respectively then the $(n+1)^{th}$ term of G.P is________

46. 
The next term of G.P. $1,2,4,8,16,...$ is:

47. 
$a_{5}$ in G.P $3,6,12,...$ will be _____

48. 
Sum of $n$ arithmetic means between a and b is ________

49. 
$a_{n}=\frac{(-1)^{n+1}}{2^{n}}$, then $a_{6}=?$

50. 
How many terms of sequence $18,15,12,....$ are needed to give a sum of 63?

51. 
If $\frac{1}{5}, \frac{1}{8}$ are two H.M between $\frac{1}{2}$ and $b$ then be equals to

52. 
Arithmetic mean between $2+\sqrt{2}$ and $2-\sqrt{2}$ is:

53. 
$\sum_{k=1}^{10} 3=?$

54. 
An infinite geometric series is convergent if _____

55. 
An arithmetic series $S_{n}$ equals to ____

56. 
The series $1+\frac{x}{2}+\frac{x^2}{4}+...$ is convergent if________

57. 
Which term of $64,60,56,52,...$ is zero?

58. 
For what value of $n$, $\frac{a^n+b^n}{a^{n-1}+b^{n-1}}$ is the A.M between a and b?

59. 
If $a_{n}-a_{n-1}=n+2$, $a_{1}=2$ then $a_{3}=?$

60. 
If $a_{n-2}=3n-11$ then nth term is

61. 
If the nth term of an A.P is $\frac{1}{2}(3-n)$ then first three terms are _________

62. 
$\sum_{k=1}^{n} 1=?$

63. 
If $a,A,b$ are in A.P then $2A=?$

64. 
Find first term of the geometric series, when $S_{n}=30,n=4,r=-2$

65. 
$\sum_{k=1}^{n} 5$ is equal to:

66. 
An arithmetic progression has a first term 12 and a fifth term 18, then the sum of first 25 term is.

67. 
$\sum_{k=1}^{n} k=?$ or (sum of first n terms)

68. 
Arithmetic Mean between two numbers $\frac{1}{a}$ and $\frac{1}{b}$ is:

69. 
The sum $\sum_{r=2}^{\infty} \frac{1}{r^2-1}$ represents:

70. 
If $a,b$ are negative then $G.M$ is:

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