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    Question

    Find the missing number in the given number series 

    55, 71, 119, 199, 311,

    ?
    A 455 Correct Answer Incorrect Answer
    B 355 Correct Answer Incorrect Answer
    C 255 Correct Answer Incorrect Answer
    D 155 Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Calculate the differences between consecutive terms: 71−55=16 119−71=48 199−119=80 311−199=112 The differences are 16,48,80,112. The second-order differences (differences of the differences) are constant: 48−16=32 80−48=32 112−80=32 Since the second-order differences are constant, the next difference is: 112+32=144 Adding this to the last term:311+144 = 455

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