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

  • question_answer
    Incomes of A, B and C are in the ratio 7 : 9 : 12 and their expenditures are in the ratio 8 : 9 : 15. If A's saving is \[\frac{1}{4}\]  of his income, then the ratio of savings of A, B and C is

    A) 56 : 99 : 69

    B) 99 : 56 : 69

    C) 69 : 56 : 99

    D) 99 : 69 : 56

    Correct Answer: A

    Solution :

    [a] Let the income of A, B and C is Rs. 7x, Rs. 9x and Rs. 12x and their expenditure is Rs. 8y, Rs. 9y and Rs. 15y respectively. According to the question, Saving of A, \[\Rightarrow \]\[7x-8y=\frac{7x}{4}\]                        …(i) \[\Rightarrow \]   \[28x-32y=7x;\] \[21x=32y\] \[\therefore \]      \[y=\frac{21x}{32}\] Saving of B, \[\Rightarrow \]\[9x-9y\] \[=9x-9\times \left( \frac{21x}{32} \right)\] (Putting the value of y)             \[=\frac{32\times 9x-9\times 21x}{32}\] \[\Rightarrow \]   \[9x-9y=\frac{99x}{32}\]                                   …(ii) Also, saving of C \[\Rightarrow \]\[12x-15y\]             \[=12x-15\times \left( \frac{21x}{32} \right)\] (Putting the value of y) \[=\frac{32\times 12x-15\times 21x}{32}=\frac{69x}{32}\]                       …(iii) Therefore ratio of their savings             \[=\frac{7x}{4};\,\,\frac{99x}{32};\,\,\frac{69x}{32}\] [by Eqs. (i), (ii), (iii)] \[=56:99:69\]


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