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10th Class Mathematics Pair of Linear Equations in Two Variables Question Bank Case Based MCQs - Pair of Linear Equations in Two Variables

  • question_answer
    How many questions did he guess?

    A) 20

    B) 22

    C) 24

    D) 26

    Correct Answer: C

    Solution :

    Let the number of questions whose answer is known to the student be x and questions attempted by guessing be y.
    Then,    x+y=120                      ...(i)
    and                                          … (ii)
    On adding Eqs. (i) and (ii), we get
                5x = 480
    \[\Rightarrow \,\,\,x=\frac{480}{5}=96\]
     Put x = 96 in Eq. (i), we get
                                                   \[96+y=120\Rightarrow y=120-96=24\]
     He guesses only 24 questions.
     


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