Two types of petrols having the prices per liter as Rs. 23 and Rs. 20 are mixed in the ratio 24 : 12. What is the price of the mixture per liter?
Rs. 22 per liter.
Rs. 23 per liter.
Rs. 21 per liter.
Rs. 25 per liter.
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 = 20, A1 = 23, n1 = 24, n2 = 12, we have 24 × (A - 23) = 12 × (20 - A), from where we get A = Rs. 22 per liter.