8th Class Mathematics Sample Paper Mathematics Sample Paper - 7

  • question_answer
    Observe the following table, where x and y are in inverse variation:
    X (i) \[{{p}_{1}}\] 200 300
    y 60 30 (ii) \[{{p}_{2}}\]
    Find the unknown quantities.

    Answer:

    Let                       \[{{x}_{1}}={{p}_{1}},{{x}_{2}}=200,{{x}_{3}}=300\]
    and                       \[{{y}_{1}}=60,{{y}_{2}}=30,{{y}_{3}}={{p}_{2}}\]
    Since, x and y are in inverse variation.                                                                                           
    (a) \[\therefore \]             \[{{x}_{1}}{{y}_{1}}={{x}_{2}}{{y}_{2}}\]
                \[\Rightarrow \]               \[{{p}_{1}}\times 60=200\times 30\]
                \[\therefore \]                  \[{{p}_{1}}=\frac{200\times 30}{60}=100\]                                                                                                      
    (b) Also,                \[{{x}_{2}}{{y}_{2}}={{x}_{3}}{{y}_{3}}\]
    \[\Rightarrow \]                       \[200\times 30=300\times {{p}_{2}}\]
    \[\therefore \]      \[{{p}_{2}}=\frac{200\times 30}{300}=20\]
         


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