MAT Exam 2020 Paper

Concept:Pure iron is obtained after removing $20\%$ waste and then taking only $25\%$ of the remaining ore.Explanation:Let the total quantity of hematite mined in the year be $x$ kg.Wasted ore $= 20\%$ of $x$, so remaining ore $= 80\%$ of $x$.Pure iron obtained $= 25\%$ of the remaining ore.Therefore, pure iron $= \frac{25}{100} \times \frac{80}{100} \times x = \frac{1}{5}x$ kg.Given that pure iron obtained in the year is $80000$ kg.So, $\frac{1}{5}x = 80000$.Hence, $x = 80000 \times 5 = 400000$ kg.Answer:The quantity of hematite mined in the year is $400000$ kg.Correct option: A. $400000$ kg.