Series Completion Problems and Answers

  • 29. 6, 11, 21, 36, 56, ... ?

    1. 81
    2. 83
    3. 95
    4. 105
    Answer :

    Option A

    Explanation:

    Pattern is +5, +10, +15, + 20. So next will be 56+25 = 81

  • 30. 6, 11, 21, 36, 56, ?
    what will replace the question mark in the series ?

    1. 75
    2. 81
    3. 85
    4. 89
    Answer :

    Option B

    Explanation:

    Pattern is +5, +10, + 15, +20

    Next number in the series will be 56 + 25 = 81

  • 31. Complete the series
    20, 19, 17, ...., 10, 5

    1. 15
    2. 16
    3. 13
    4. 14
    Answer :

    Option D

    Explanation:

    Pattern is, -1, -2, ..,.. , -5

    So -3 and -4 will fill the blanks to make it a pattern.

    Next number will be 17-3 = 14

  • 32. In the series 3, 9, 15.. what will be the 21st term ?

    1. 123
    2. 126
    3. 129
    4. 136
    Answer :

    Option A

    Explanation:

    We can judge that it is A.P.
    With 6 as difference
    nth term in A.P. = a+(n-1)d
    a= 3, n = 21, d = 6
    So, 21st term will be = 3+(20)6 = 123

  • 33. 1,6,15,(...),45,66,91

    1. 26
    2. 28
    3. 29
    4. 34
    Answer :

    Option B

    Explanation:

    Pattern in the series is, +5, +9, .., .., +21, +25
    So 4 is getting increased at every term addition.
    Missing term in the series will be 15+(9+4)
    = 15+13 = 28

  • 34. 1,1,3,9,6,36,10,100,(..),225

    1. 12
    2. 13
    3. 14
    4. 15
    Answer :

    Option D

    Explanation:

    Given sequence is combination of two series
    Series 1 : 1,3,6,10,..
    Series 2 : 1,9,36,100,225

    In series 1 pattern is +2, +3, +4. So next term will be
    10+5 = 15

  • 35. 21,25,33,49,81, ?

    1. 140
    2. 145
    3. 147
    4. 159
    Answer :

    Option B

    Explanation:

    Pattern is, +4, +8, +16, +32, so next will be +64
    81+64 = 145

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