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SSC Quantitative Aptitude Average Question Bank Average (I)

  • question_answer
    The average of first three numbers is double of the fourth number. If the average of all the four numbers is 12, then find the 4th number.

    A) 16

    B) 46

    C) 20

    D) 18

    Correct Answer: B

    Solution :

    [b] Let first, second, third and fourth numbers be a, b, c and d, respectively. Then,    \[\frac{a+b+c}{3}=2d\] Now,     \[\frac{a+b+c+d}{4}=12\] \[\Rightarrow \]   \[\frac{6d+d}{4}=12\]\[\Rightarrow \]\[d=\frac{48}{7}\]


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