RRB Group D Mixture & Alligation

Alligation is a quick method to find the ratio of mixing two items when we know their individual values and the mean (average) value of the mixture. It works on the principle that gain of one quantity equals loss of another quantity

The ratio of quantities is inversely proportional to their differences from the mean 2. Cheaper quantity × Its difference from mean = Dearer quantity × Its difference from mean 3. For replacement problems, use: Final strength = Initial strength × (1 - R/C)^n where R = replaced quantity, C = total capacity, n = number of operations

mixing two different priced items, alcohol-water mixtures, milk-water problems, successive mixing, and replacement of mixtures

Draw a cross diagram. Put mean in center, cheaper value top-left, dearer value bottom-left. Differences go on right side. This gives the mixing ratio directly

the ratio is OPPOSITE to what you might think. If mean is closer to cheaper value, you need MORE of the cheaper item, not less. Always write (Mean - Cheaper) : (Dearer - Mean) for the ratio of Cheaper : Dearer.