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SSC Sample Paper Mock Test-15 SSC CGL Tear-II Paper-1

  • question_answer
    The ratio of the numbers of boys and girls in a school was 5 : 3. Some new boys and girls were admitted to the school, in the ratio 5 : 7. At this, the total number of students in the school became 1200 and the ratio of boys to girls changed to 7 : 5. The number of students in the school before new admissions was

    A) 700      

    B)  720     

    C)  900     

    D)  960

    Correct Answer: D

    Solution :

    Let the original number of boys and girls be 5x and 3x respectively and that of new boys and girls be 5y and 7y respectively. \[\therefore \]      \[5x+3x+5y+7y=1200\] \[\Rightarrow \]   \[2x+3y=300\]              ?(i) and       \[\frac{5x+5y}{3x+7y}=\frac{7}{5}\]       \[\Rightarrow \]   \[25x+25y=21x+49y\] \[\Rightarrow \]   \[4x=24y\] \[\Rightarrow \]   \[x=6y\] From Eq. (i), we get \[4x+6y=600\] \[\Rightarrow \]   \[5x=600\]\[\Rightarrow \]\[x=120\] Original number of students\[=8x=960\]


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