In what ratio must lentils costing ₹56 per kg be mixed with lentils costing ₹67 per kg, so that the mixture is worth ₹64 per kg?

💡 Solution & Explanation

Use alligation: the cheaper part : the dearer part = (dearer price − mixture price) : (mixture price − cheaper price) = (67 − 64) : (64 − 56) = 3 : 8, which simplifies to 3 : 8. Check: mixing in that ratio gives an average of ₹64 per kg. Writing the differences the other way round is the most common mistake.