A) \[45\,cm\]
B) \[90\,cm\]
C) \[100\,cm\]
D) \[80\,cm\]
Correct Answer: B
Solution :
Let the length of rectangular floor is x cm, \[\because \] Breadth \[=x\times \frac{4}{5}=\frac{4x}{5}\] \[\therefore \] Area of floor \[=x\times \frac{4x}{5}=500\] \[4{{x}^{2}}=2500\Rightarrow \,\,{{x}^{2}}=625\Rightarrow x=\sqrt{625}=25\] Length of floor \[=25\text{ }cm\] Breadth of floor \[=25\times \frac{4}{5}=20\,cm.\] \[\therefore \] Perimeter \[=2(l+b)\] \[=\,2(25+20)=\underline{\mathbf{90}\,\mathbf{cm}}\]You need to login to perform this action.
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