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

February 28, 2026

1. 
If $a,A,b$ are in A.P then $2A=?$

2. 
How many terms of sequence $18,15,12,....$ are needed to give a sum of 63?

3. 
An infinite sequence has no __________

4. 
$\sum_{k=1}^{n} 5$ is equal to:

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

6. 
$\sum_{k=1}^{3} k^2$ is equal to:

7. 
For what value of $n$, $\frac{a^n+b^n}{a^{n-1}+b^{n-1}}$ is the A.M between a and b?

8. 
In $\frac{1}{4.7}+\frac{1}{7.10}+\frac{1}{10.13}+$...., then $n^{th}$ term is:

9. 
The $10^{th}$ term of $\frac{1}{2},\frac{1}{5},\frac{1}{8},...,$ is:

10. 
In geometric sequence nth term equal to

11. 
If $\frac{4}{7}$ be the third term of H.P, then third term of A.P is:

12. 
$\sum_{k=1}^{n} 1=?$

13. 
Geometric mean of Two positive numbers a and b

14. 
$\sum_{k=1}^{10} 3=?$

15. 
For an infinite geometric series for which $|r|

16. 
$\sum_{k=1}^{n} k^{3}=?$ or $(1^3+2^3+3^3+...+n^3)=?$

17. 
If $\frac{1}{a},\frac{1}{b}$ and $\frac{1}{c}$ are in A.P then common difference is equal to_________.

18. 
$\sum_{k=1}^{n} k^{2}=?$ or $(1^2+2^2+3^2+...+n^2)=?$

19. 
Sum of $n$ terms of an A.P is ____

20. 
The sigma notation for the sum $-2+4-6+8$ is:

21. 
Sum of the series $\frac{5}{(13)^{1}}+\frac{55}{(13)^{2}}+\frac{555}{(13)^{3}}+\frac{5555}{(13)^{4}}+...$ up to $\infty$ is:

22. 
If $a_{n}-a_{n-1}=n+2$, $a_{1}=2$ then $a_{3}=?$

23. 
The nth term of sequence $\frac{1}{3},\frac{2}{5},\frac{3}{7},....$ is:

24. 
G.Ms between $1$ and $\frac{1}{3}$ is:

25. 
Arithmetic mean between $2+\sqrt{2}$ and $2-\sqrt{2}$ is:

26. 
$a_{n}=\frac{(-1)^{n+1}}{2^{n}}$, then $a_{6}=?$

27. 
An infinite geometric series is convergent if _____

28. 
Arithmetic Mean between two numbers $\frac{1}{a}$ and $\frac{1}{b}$ is:

29. 
If $\frac{1}{a},\frac{1}{b}$ and $\frac{1}{c}$ are in G.P then common ratio is equal to_________

30. 
Sum of the series $1+3+5+7+9+11+...+n$ terms is:

31. 
A.M between $\frac{a}{2}$ and $\frac{2}{a}$ is

32. 
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:

33. 
If $y=\frac{2}{3}x+\frac{4}{9}x^2+\frac{8}{27}x^3+....$ then interval of convergence is____

34. 
If $\frac{1}{a},\frac{1}{b}$ and $\frac{1}{c}$ are in A.P then b is equal to_________.

35. 
What is the sum of infinite G.P; $2,\sqrt{2},1,...?$

36. 
If $a,b,c$ are in A.P, then $3^{a},3^{b},3^{c}$ are in:

37. 
$\sum_{k=1}^{n} k=?$ or (sum of first n terms)

38. 
The sum $\sum_{r=2}^{\infty} \frac{1}{r^2-1}$ represents:

39. 
The formula $S_{n}=\frac{a(r^{n}-1)}{r-1}$ is used for sum of a terms of G.P. if ____

40. 
Which term of $64,60,56,52,...$ is zero?

41. 
If $a,b$ are negative and G.M is also negative

42. 
The arithmetic mean in the sequence $-7$,_,_,$5$ are

43. 
The $(n+1)th$ term of an A.P is _______

44. 
If the nth term of an A.P is $\frac{1}{2}(3-n)$ then first three terms are _________

45. 
The series $1+\frac{x}{2}+\frac{x^2}{4}+...$ is convergent if________

46. 
Find the $26^{th}$ terms from the end of A.P : $2,7,12,17,...,222.$

47. 
Predict the general term for the sequence $\frac{4}{3},\frac{4}{9},\frac{4}{27},\frac{4}{81},...$

48. 
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:

49. 
The reciprocal of the term of H.P is.....

50. 
Sequence is denoted by______

51. 
An arithmetic progression has a first term 12 and a fifth term 18, then the sum of first 25 term is.

52. 
$0.1+0.01+0.001+0.0001+....$ the sum is:

53. 
$\frac{1}{k}, \frac{1}{2k+1}, \frac{1}{4k-1}$ are in H.P then $k=?$

54. 
Find first term of the geometric series, when $S_{n}=30,n=4,r=-2$

55. 
If $x,y,z$ are in H.P. Sequence then value of z is ______

56. 
If $\frac{1}{5}, \frac{1}{8}$ are two H.M between $\frac{1}{2}$ and $b$ then be equals to

57. 
The nth term of an A.P with usual notions is ______

58. 
An arithmetic series $S_{n}$ equals to ____

59. 
If $a,b,c$ are in G.P and $a>0,b>0,c>0,$ then the reciprocals of $a,b,c$ form ______

60. 
Sum of $n$ arithmetic means between a and b is ________

61. 
If $a_{n-2}=3n-11$ then nth term is

62. 
The next term of G.P. $1,2,4,8,16,...$ is:

63. 
$S_{n}=1+2+3+...+n$ can also be shown as_______

64. 
A sequence $a_{n}$ is an arithmetic sequence if $\forall \, n\in\,\mathbb{N}$ and $n>1$:

65. 
If A,G,H have their usual meanings and 'a' and 'b' are positive distinct real numbers and $G>0$, then:

66. 
The general term of the given series $\frac{1}{1.3}+\frac{1}{2.5}+\frac{1}{3.7}+...$ is

67. 
If $a_{1}$ and $r$ are the first term and common ratio respectively then the $(n+1)^{th}$ term of G.P is________

68. 
$\sum_{j=1}^{10} \sum_{i=1}^{15} k =?$

69. 
The A.M between two numbers a and b is ________

70. 
What is sum of n term with nth term $a_{n} = 4n+1$

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