Sequences And Series CBSE Questions & Answers

Sequences And Series

This is Mathematics Class 11 Sequences and Series CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
If the numbers a, b, c are in A.P., b, c, d are in G.P. and c, d , e are in H.P., then a, c, e are in
  • A
    G.P.
    Correct
  • B
    H.P.
  • C
    none of these
  • D
    A.P.
2
If x, y, z are in A.P., then (x + 2y – z) (x + z – y) (z + 2y – x) is equal to
  • A
    4 x y z
    Correct
  • B
    2 x yz
  • C
    x y z
  • D
    none of these
3
If a, b , c are in A.P. and also \({1 \over a},{1 \over b},{1 \over c}\) are in A. P., then
  • A
    a = b = c
    Correct
  • B
    \(a \ne b \ne c\)
  • C
    \(a = b \ne c\)
  • D
    \(a \ne b = c\)
4
The sum of terms equidistant from the beginning and end in A.P. is equal to
  • A
    last term
  • B
    none of these
  • C
    first term
  • D
    sum of the first and the last terms
    Correct
5
Sum of first 5 terms of an A.P. is one fourth of the sum of next five terms. If the first term = 2, then the common difference of the A.P. is
  • A
    3
  • B
    - 6
    Correct
  • C
    none of these
  • D
    6
6
The first, second and last terms of an A.P. are a, b and 2 a. The number of terms in the A.P. is
  • A
    \({b \over {b - a}}\)
    Correct
  • B
    \({a \over {b + a}}\)
  • C
    \({b \over {b + a}}\)
  • D
    \({a \over {b - a}}\)
7
The sum of all the two-digit numbers is
  • A
    none of these
  • B
    4905
    Correct
  • C
    1605
  • D
    4895
8
Sum of all 2 digit odd numbers is
  • A
    4905
  • B
    2530
  • C
    5049
  • D
    2475
    Correct
9
The number of terms common to the two A.P.s 2 + 5 + 8 + 11 + … + 98 and 3 + 8+ 13 + 18+ 23 + … + 198
  • A
    none of these
  • B
    40
  • C
    33
  • D
    7
    Correct
10
The values of x for which the solutions of the equation cos \(\theta = x,\theta \ge 0\) form an A.P. are
  • A
    none of these
  • B
    - 1 and 1
  • C
    0, 1 and – 1
    Correct
  • D
    0 and 1
11
If \(a\; \in \;\;R,\) then the roots of the equation tan x = a are in
  • A
    G.P.
  • B
    A.P.
    Correct
  • C
    none of these
  • D
    H.P.
12
The values of ‘a’ for which the roots of the equation sin x = a in A.P. are
  • A
    0, 1 and – 1
    Correct
  • B
    - 1 and 1
  • C
    0 and 1
  • D
    none of theses
13
The sum of first four terms of an A. P. is 56 and sum of last four terms is 112. If the first term is 11, then the number of terms is
  • A
    1
    Correct
  • B
    10
  • C
    none of these
  • D
    12
14
The ratio of the \({{\rm{7}}^{{\rm{th}}}}\) to the ( n –1)th mean between 1 and 31, when n arithmetic means are inserted between them, is 5 : 9. The value of n is
  • A
    12
  • B
    13
  • C
    15
  • D
    14
    Correct
15
The sum of first n terms of the series 1 – 1 + 1 – 1 + … is
  • A
    \( \pm 1\)
  • B
    \({\left( { - 1} \right)^n}\)
  • C
    1 if n is odd and 0 when n is even
    Correct
  • D
    - 1