10th Class Mathematics Quadratic Equations Question Bank Quadratic Equations

  • question_answer
    Rs.6500 were divided equally among a certain number of persons. If there had been 15 more persons, each would have got Rs. 30 less. Find the original number of persons.

    A)  50                              

    B)                     60                              

    C)                     45                              

    D)                     55                              

    Correct Answer: A

    Solution :

    Let x be the number of persons and y be the amount received by each person. According to the question,\[xy=6500~\]  ...(1) Also,  \[(x+15)\,(y-30)=6500\]            ...(2) \[\Rightarrow \]  \[xy-30x+15y-450=6500\] \[\Rightarrow \]\[6500-30x+15y-450=6500\] [From (1)] \[\Rightarrow \] \[2x-y+30=0\] \[\Rightarrow \] \[2x-\frac{6500}{x}+30=0\]            [From (1)] \[\Rightarrow \]  \[2{{x}^{2}}-6500+30x=0\] \[\Rightarrow \]  \[{{x}^{2}}+15x-3250=0\] \[\Rightarrow \] \[(x-50)\,(x+65)=0\] \[\Rightarrow \] \[x=50\] or  \[x=-65\] Since, number of persons cannot be negative. Hence, number of persons = 50


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