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

January 14, 2026

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

2. 
If $a,b,c$ are in A.P, then $3^{a},3^{b},3^{c}$ are in:

3. 
A.M between $\frac{a}{2}$ and $\frac{2}{a}$ is

4. 
$\sum_{k=1}^{3} k^2$ is equal to:

5. 
For what value of $n$, $\frac{a^n+b^n}{a^{n-1}+b^{n-1}}$ is the A.M between a and b?

6. 
If $a_{n-2}=3n-11$ then nth term is

7. 
A sequence $a_{n}$ is an arithmetic sequence if $\forall \, n\in\,\mathbb{N}$ and $n>1$:

8. 
For an infinite geometric series for which $|r|

9. 
In geometric sequence nth term equal to

10. 
Arithmetic mean between $2+\sqrt{2}$ and $2-\sqrt{2}$ is:

11. 
Predict the general term for the sequence $\frac{4}{3},\frac{4}{9},\frac{4}{27},\frac{4}{81},...$

12. 
The $10^{th}$ term of $\frac{1}{2},\frac{1}{5},\frac{1}{8},...,$ is:

13. 
$0.1+0.01+0.001+0.0001+....$ the sum is:

14. 
The nth term of an A.P with usual notions is ______

15. 
If $\frac{1}{a},\frac{1}{b}$ and $\frac{1}{c}$ are in G.P then common ratio is equal to_________

16. 
Which term of $64,60,56,52,...$ is zero?

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

18. 
Sum of the series $\frac{5}{(13)^{1}}+\frac{55}{(13)^{2}}+\frac{555}{(13)^{3}}+\frac{5555}{(13)^{4}}+...$ up to $\infty$ is:

19. 
The sum $\sum_{r=2}^{\infty} \frac{1}{r^2-1}$ represents:

20. 
The formula $S_{n}=\frac{a(r^{n}-1)}{r-1}$ is used for sum of a terms of G.P. if ____

21. 
The A.M between two numbers a and b is ________

22. 
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:

23. 
An infinite sequence has no __________

24. 
An infinite geometric series is convergent if _____

25. 
Sum of the series $1+3+5+7+9+11+...+n$ terms is:

26. 
If $a_{1}$ and $r$ are the first term and common ratio respectively then the $(n+1)^{th}$ term of G.P is________

27. 
Sum of $n$ terms of an A.P is ____

28. 
Sequence is denoted by______

29. 
If $a,A,b$ are in A.P then $2A=?$

30. 
G.Ms between $1$ and $\frac{1}{3}$ is:

31. 
The sigma notation for the sum $-2+4-6+8$ is:

32. 
The nth term of sequence $\frac{1}{3},\frac{2}{5},\frac{3}{7},....$ is:

33. 
If A,G,H have their usual meanings and 'a' and 'b' are positive distinct real numbers and $G>0$, then:

34. 
Geometric mean of Two positive numbers a and b

35. 
$S_{n}=1+2+3+...+n$ can also be shown as_______

36. 
If $\frac{4}{7}$ be the third term of H.P, then third term of A.P is:

37. 
The general term of the given series $\frac{1}{1.3}+\frac{1}{2.5}+\frac{1}{3.7}+...$ is

38. 
What is the sum of infinite G.P; $2,\sqrt{2},1,...?$

39. 
How many terms of sequence $18,15,12,....$ are needed to give a sum of 63?

40. 
Sum of $n$ arithmetic means between a and b is ________

41. 
Arithmetic Mean between two numbers $\frac{1}{a}$ and $\frac{1}{b}$ is:

42. 
$\sum_{k=1}^{n} 5$ is equal to:

43. 
What is sum of n term with nth term $a_{n} = 4n+1$

44. 
An arithmetic progression has a first term 12 and a fifth term 18, then the sum of first 25 term is.

45. 
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:

46. 
The arithmetic mean in the sequence $-7$,_,_,$5$ are

47. 
An arithmetic series $S_{n}$ equals to ____

48. 
$a_{5}$ in G.P $3,6,12,...$ will be _____

49. 
If $x,y,z$ are in H.P. Sequence then value of z is ______

50. 
$\sum_{k=1}^{n} k^{2}=?$ or $(1^2+2^2+3^2+...+n^2)=?$

51. 
The reciprocal of the term of H.P is.....

52. 
If the nth term of an A.P is $\frac{1}{2}(3-n)$ then first three terms are _________

53. 
If $\frac{1}{a},\frac{1}{b}$ and $\frac{1}{c}$ are in A.P then common difference is equal to_________.

54. 
$\sum_{k=1}^{n} k^{3}=?$ or $(1^3+2^3+3^3+...+n^3)=?$

55. 
$\sum_{j=1}^{10} \sum_{i=1}^{15} k =?$

56. 
$\sum_{k=1}^{n} k=?$ or (sum of first n terms)

57. 
The $(n+1)th$ term of an A.P is _______

58. 
If $a,b$ are negative and G.M is also negative

59. 
$a_{n}=\frac{(-1)^{n+1}}{2^{n}}$, then $a_{6}=?$

60. 
Find first term of the geometric series, when $S_{n}=30,n=4,r=-2$

61. 
$\sum_{k=1}^{n} 1=?$

62. 
If $y=\frac{2}{3}x+\frac{4}{9}x^2+\frac{8}{27}x^3+....$ then interval of convergence is____

63. 
If $a,b,c$ are in G.P and $a>0,b>0,c>0,$ then the reciprocals of $a,b,c$ form ______

64. 
The series $1+\frac{x}{2}+\frac{x^2}{4}+...$ is convergent if________

65. 
If $a_{n}-a_{n-1}=n+2$, $a_{1}=2$ then $a_{3}=?$

66. 
$\sum_{k=1}^{10} 3=?$

67. 
The next term of G.P. $1,2,4,8,16,...$ is:

68. 
If $\frac{1}{5}, \frac{1}{8}$ are two H.M between $\frac{1}{2}$ and $b$ then be equals to

69. 
In $\frac{1}{4.7}+\frac{1}{7.10}+\frac{1}{10.13}+$...., then $n^{th}$ term is:

70. 
$\frac{1}{k}, \frac{1}{2k+1}, \frac{1}{4k-1}$ are in H.P then $k=?$

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