Question

An ore contains 25% of an alloy that has 90% Other than this, in the remaining 75% of the there is no iron. How many kilograms of the ore needed to obtain 60 kg of pure iron?

• A. 250 kg
• B. 275 kg
• C. 300 kg
• D. 266.66 kg

Answer 1

The correct option is D 266.66 kg

Let amount of ore is 100 kg
25% or 25 kg has 90% iron

$=\frac{25\times 90}{100}=22.5kgiron$
75% or 75 kg has no iron
To obtain 22.5 kg 100 kg ore is required
So to obtain 60 kg

$\frac{100}{22.5}\times 60=266.66kg$