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 a, b, c are in A. P. as well as in G.P.; then
  • A
    a = b = c
    Correct
  • B
    \(a \ne b \ne c\)
  • C
    \(a = b \ne c\)
  • D
    \(a \ne b = c\)
2
The 20th term of the series \(2 \times 4 + 4 \times 6 + 6 \times 8 + ...\) is
  • A
    1680
    Correct
  • B
    1600
  • C
    840
  • D
    420
3
the ratio of first to the last of n A.m.’s between 5 and 25 is 1 : 4. The value of n is
  • A
    11
  • B
    10
  • C
    none of these
  • D
    9
    Correct
4
The next term of the sequence 1, 3, 6, 10, …. Is
  • A
    16
  • B
    15
    Correct
  • C
    14
  • D
    13
5
If A, G, H denote respectively the A.M., G.M. and H.M. between two unequal positive quantities then
  • A
    A \(<\) H \(<\) G
  • B
    H \(<\) G \(<\) A
    Correct
  • C
    G \(<\) H \(<\) A
  • D
    A \(<\) G \(<\) H
6
If A, G and H denote respectively, the A.M., G.M. and H.M. between two positive numbers a and b, then A - G is equal to
  • A
    none of these
  • B
    a – b
  • C
    \({{2\;a\;b} \over {a + b}}\)
  • D
    \({1 \over 2}{\left( {\sqrt a - \sqrt b } \right)^2}\)
    Correct
7
If a, b, c, d are in H.P., then ab + bc + cd is
  • A
    ( a + b) ( c + d)
  • B
    3 a d
    Correct
  • C
    3 b d
  • D
    3 a c
8
The sum of all 2-digited numbers which leave remainder 1 when divided by 3 is
  • A
    none of these
  • B
    1605
    Correct
  • C
    1605
  • D
    1616
9
The number of numbers between 105 and 1000 which are divisible by 7 is
  • A
    142
  • B
    128
  • C
    127
    Correct
  • D
    none of these
10
The next term of the sequence 1, 5, 14, 30, 55, …… is
  • A
    90
  • B
    80
  • C
    91
    Correct
  • D
    95
11
If the numbers a, b, c, d, e form an A.P. then the value of a – 4b + 6 c – 4 d + e is
  • A
    2
  • B
    1
  • C
    0
    Correct
  • D
    none of these
12
The sum of all non-reducible fractions with the denominator 3 lying between the numbers 5 and 8 is
  • A
    39
    Correct
  • B
    41
  • C
    31
  • D
    52
13
The next term of the sequence 1, 1, 2, 4, 7, 13,…. Is
  • A
    21
  • B
    none of these
  • C
    19
  • D
    24
    Correct
14
An A.P. consists of n (odd) terms and its middle term is m. Then the sum of the A.P. is
  • A
    mn
    Correct
  • B
    \({1 \over 2}mn\)
  • C
    2 mn
  • D
    \(m{n^2}\)
15
The terms equidistant from a given term of an A.P. are multiplied together, then the difference of the successive terms of the series so formed are in
  • A
    equal
  • B
    H.P.
  • C
    G.P.
  • D
    A.P.
    Correct