Question

Out of the total production of iron from hematite ore of iron, 20% of the ore gets wasted, and the remaining ore, only 25% is pure iron. If the iron obtained in a year from a mine of hematite 80,000 kg, then the quantity of hematite mined that mine in the year is

• A. 5,00,000 kg
• B. 4,00,000 kg
• C. 4,50,000 kg
• D. None of these

Answer 1

The correct option is B 4,00,000 kg

Let x kg ore is there

20% washed away so remaining is 80% i.e. 4/5x

$outof\frac{4}{5}x,25\%ispureiron$

$\frac{25}{100}\times \frac{4}{5}x=\frac{1}{5}x$

$i.e.\frac{1}{5}xkgisobtainedfromxkgthen1kgisobtainedfrom5kg$

$\therefore$ 80000 kg is obtained from

$5\times 80000=400000kg$