Advertisement

### Question

9 liters of Petrol costing Rs. 21/liter is mixed with 15 liters of Kerosene costing Rs. 13/liter. What is the price of the mixture per liter?

**A**

Rs. 16 per liter.

**B**

Rs. 17 per liter.

**C**

Rs. 15 per liter.

**D**

Rs. 19 per liter.

**Soln.**

**Ans: a**

We shall use the alligation formula. If a sample n_{1} has an average price of A_{1}, and another sample n_{2} has an average price of A_{2}, then the price of the mixture, A, is determined by the alligation formula as: n_{1}(A - A_{1}) = n_{2}(A_{2} - A). Putting A_{2} = 13, A_{1} = 21, n1 = 9, n2 = 15, we have 9 × (A - 21) = 15 × (13 - A), from where we get A = Rs. 16 per liter.