How to solve Removal and replacement questions
How to solve Removal and replacement questions We often get questions involving removal and replacement of mixtures where a part of a mixture is removed and replaced by some other solution. Say, a vessel contains different constituents in some given ratio. A fraction of the solution is removed and some quantity of some constituent is added to the solution. This process is repeated multiple times and the final ratio of constituents in the mixture has to be determined. Though this looks very complicated, we can solve it simply, in fact, in a single line! We just need to understand the fact that if a fraction, f of the solution is removed, the same fraction of each constituent also gets removed, and hence, the fraction (1-f) of each constituent is left, and as a result, after removal, the ratio of the constituents remains unchanged. This is very easy to understand. Say, you have a sugar solution in a glass and you drink a part of it. The remaining part would t...