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JEE Main & Advanced AIEEE Solved Paper-2007

  • question_answer
    The average marks of boys in a class is 52 and that of "girls is 42. The average marks of boys and girls combined is 50. The percentage of boys in the class is       AIEEE  Solved  Paper-2007

    A)  40                         

    B)         20                         

    C)         80                         

    D)         60

    Correct Answer: C

    Solution :

    Total number of boys and girls = Average \[\times \] Number of boys + Average \[\times \] Number of girls. Let the number of boys and girls be\[x\]and y. \[\therefore \]\[52x+42y=50(x+y)\] \[\Rightarrow \]\[52x+42y=50x+50y\] \[\Rightarrow \]\[2x=8y\]\[\Rightarrow \]\[x=4y\] \[\therefore \]Total number of students in the class \[=x+y=4y+y=5y\] \[\therefore \] Required percentage of boys \[=\frac{4y}{5y}\times 100%=80%\]


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