Punjab Medical Punjab - MET Solved Paper-2007

  • question_answer
    A stretched wire of length \[110cm\] is divided into three segments whose frequencies are in ratio\[1:2:3\]. Their length must be

    A)  20 cm; 30 cm; 60 cm

    B)  60 cm; 30 cm; 20 cm

    C)  60 cm; 20 cm; 30 cm

    D)  30 cm; 60 cm; 20 cm

    Correct Answer: B

    Solution :

    Given,\[{{l}_{1}}+{{l}_{2}}+{{l}_{3}}=110\,\,cm\] and        \[{{n}_{1}}{{l}_{1}}={{n}_{2}}{{l}_{2}}={{n}_{3}}{{l}_{3}}\]                              \[{{n}_{1}}:{{n}_{2}}:{{n}_{3}}::1:2:3\] \[\because \]     \[\frac{{{n}_{1}}}{{{n}_{2}}}=\frac{1}{2}=\frac{{{l}_{2}}}{{{l}_{1}}}\]  \[\Rightarrow \]   \[{{l}_{2}}=\frac{{{l}_{1}}}{2}\] and        \[\frac{{{n}_{1}}}{{{n}_{3}}}=\frac{1}{3}=\frac{{{l}_{3}}}{{{l}_{1}}}\]  \[\Rightarrow \]   \[{{l}_{3}}=\frac{{{l}_{1}}}{3}\] \[\therefore \]  \[{{l}_{1}}+\frac{{{l}_{1}}}{2}+\frac{{{l}_{1}}}{3}=110\] So,\[{{l}_{1}}=60\,\,cm,\,\,{{l}_{2}}=30\,\,cm,\,\,{{l}_{3}}=20\,\,cm\]


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