6th Class Mathematics Mensuration Question Bank Menstruation

  • question_answer
    The length of a rectangle is increased by 60% By what percentage would be the width have to be decreased to maintain the same area?

    A)  \[37\frac{1}{2}%\]               

    B)    60%

    C)  75%               

    D)    120%

    Correct Answer: A

    Solution :

         Let the initial length and width are l and b respectively. Final length \[=l\times \frac{160}{100}\] Final width = b' (say) Initial area = final area \[l\times b=l\times \frac{160}{100}\times b'\Rightarrow \,b'\,=\frac{100}{160}\,b=\frac{5}{8}b\] Percentage decriment in width \[=\frac{b-b'}{b'}\,\times 100=\frac{b-\frac{5}{8}b}{b}\times 100%\] \[=37.5%\]


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