From 40 tons of iron ore, 20 tons of steel are smelted containing 6% impurity.

From 40 tons of iron ore, 20 tons of steel are smelted containing 6% impurity. What is the% of impurity in the ore itself?

1. Let’s determine how many tons of impurities are in 20 tons of steel. To do this, you need to multiply the initial number of tons of steel by the percentage of impurities in the steel, and divide the result by 100%:
20 t * 6% / 100% = 1.2 t.
2. Determine how many percent is 1.2 tons of impurities from 40 tons of iron ore. To do this, the number of tons of impurities must be divided by the number of tons of iron ore, and the result obtained must be multiplied by 100%:
1.2 t / 40 t * 100% = 3%.
Answer: Iron ore contains 3% impurities.