18 Kg of Grade I sugar costing Rs. 7/Kg is mixed with 9 Kg of Grade II sugar costing Rs. 16/Kg. What is the price of the mixture per Kg?
Rs. 10 per Kg.
Rs. 11 per Kg.
Rs. 9 per Kg.
Rs. 13 per Kg.
We shall use the alligation formula. If a sample n1 has an average price of A1, and another sample n2 has an average price of A2, then the price of the mixture, A, is determined by the alligation formula as: n1(A - A1) = n2(A2 - A). Putting A2 = 16, A1 = 7, n1 = 18, n2 = 9, we have 18 × (A - 7) = 9 × (16 - A), from where we get A = Rs. 10 per Kg.