(IGP) IAS Pre Paper - 2: GS - Basic Numeracy - Alligation or Mixture

Introduction

It is the rule that is used to determine the mean value of the mixture when the prices of the individual items being mixed together and the proportion in which they are being mixed are given. Here, the value of the mixture is always higher than the lowest value and lower than the higher value of the items being mixed. According to the Rule of Alligation

(Cheaper quantity : Dearer quantity) = (y – m) : (m – x)
Where, mean price (m) is the cost price of a unit quantity of the mixture. Also, if a container contains x units of liquid from which y units are taken out and replaced by water. After n

Example 1: Howmany kilograms of rice costing Rs. 18 per kgmust bemixed with 30 kg of rice costing Rs. 14 per kg, so that the resultant mixture cost Rs. 15 per kg.
Solution. Applying the rule of alligation, we have

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