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7th Class Mental Ability Numbers Question Bank Number System

  • question_answer
    Peter has a rod such that \[\frac{\mathbf{1}}{\mathbf{8}}\]m of it is yellow, \[\frac{\mathbf{1}}{\mathbf{2}}\]m of the remaining is green and \[\mathbf{3}\frac{\mathbf{1}}{\mathbf{2}}\] m of the remaining is white: The length of rod is which of the following?

    A) 8 m       

    B)   4 m

    C) 3 m                  

    D)   7 m

    E) None of these

    Correct Answer: A

    Solution :

    Explanation Let the length of rod be x Part of rod which is yellow \[=\,\,\frac{1}{8}x=\frac{x}{8}\] Part of rod which is green \[=\,\,\frac{1}{2}x-\frac{7x}{8}=\frac{7x}{16}\] Remaining part of rod \[=\,\,x-\left( \frac{x}{8}+\frac{7x}{16} \right)\,\,\,=x-\frac{9x}{16}=\frac{7x}{16}\] According to question, \[\Rightarrow \,\,\,\,\frac{7x}{16}=\frac{7}{2}\,\,\Rightarrow \,\,x=8\,\,m.\]             


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