Question

An ore contains 12% copper. How many kilograms of the ore are required to get 69 kg of copper?

Answer 1

Let x kg be the amount of the required ore.

Then, 12% of x kg = 69 kg
⇒ $\left(\frac{12}{100}\times x\right)$ kg = 69 kg
⇒ x = $\left(\frac{69\times 100}{12}\right)$ kg = 575 kg

Hence, 575 kg of ore is required to get 69 kg of copper.