SSC Quantitative Aptitude Ratio and Proportion Question Bank Ratio and Proportion (II)

  • question_answer
    The quantity that must be added to each term of \[a:b,\] so as to make it \[c:d\] is

    A) \[\frac{ab-cd}{a-b}\]

    B) \[\frac{ac-bd}{a+b}\]

    C) \[\frac{ad-bc}{c+d}\]

    D) \[\frac{ad-bc}{c-d}\]

    Correct Answer: D

    Solution :

    [d] Let the quantity be x. Then, \[\frac{a+x}{b+x}=\frac{c}{d}\] \[\Rightarrow \]   \[(a+x)\,d=(b+x)c\] \[\Rightarrow \]   \[ad+dx=bc+cx\] \[\Rightarrow \]   \[ab-bc=cx-dx\] \[\Rightarrow \]   \[ad-bc=x\,\,(c-d)\]\[\therefore \]\[x=\frac{ad-bc}{c-d}\]


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