Subject

    Quantitative Aptitude

    Topic

    Average

    The average of the two-digit numbers, which remain the same when the dibits inter-change their positions, is :

    ক)
    42
    খ)
    51
    গ)
    55
    ঘ)
    72

    Explanation

    Average = (11 + 22 + 33 + 44 + 55 + 66 + 77 + 88 + 99) / 9 =( (11 + 99) + (22 + 88) + (33 + 77) + (44 + 66) + 55) / 9 = (4 ×\times 110 + 55)/9 =  495 / 9 = 55.

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