Civil Services Examination · Question 79
There are two chemicals which do not react with each other. A container contains 10 litres of the chemical A. One litre of this chemical is removed from it and one litre of the chemical B is poured. Then one litre of the mixture is removed from the container and one litre of B is poured. If this process of replacing one litre of the mixture by one litre of B is performed once more, then what is the volume of B that is present in the container approximately (in percentage)?
Show answer & explanation
Answer: (B) 27
Explanation
After three replacements, A left = 10 × (9/10)³ = 7.29 L, so B = 2.71 L ≈ 27%.