In 1 kg mixture of sand and iron, 20% is iron. How much sand should be added so that the proportion of iron becomes 10%?	Choose the correct choice: A) 1 kg B) 200gms C) 1.8kg D) 4.5kg E) 500gms
There are 200 grams of iron in 1 kg (1,000 grams) of the mixture.   If we add x grams of sand, the total amount would be 1,000 + x grams of mixture and we need 200 grams of iron to be 10% of that: 0.1(1,000 + x) = 200 --&gt; x = 1,000.   Answer: A.   Or: for 200 grams of iron to be 10 of the mixture, the mixture must be 2,000 grams, thus 2,000 - 1,000 = 1,000 grams of sand should be added.   1 kgnswer: 1 kg.
<result>A</result>
In 1 kg mixture of sand and iron, 20% is iron. How much sand should be added so that the proportion of iron becomes 10%?