In what ratio should rice at Rs. 7.20/kg be mixed with rice at Rs. 5.70/kg to get a mixture worth Rs. 6.30/kg?

Problem restatementMix two grades of rice at Rs. 7.20/kg and Rs. 5.70/kg to obtain a mixture at Rs. 6.30/kg. Find the mixing ratio.

Given data

• Higher price (H) = 7.20
• Lower price (L) = 5.70
• Mean price (M) = 6.30

Concept/ApproachUse the rule of alligation. Quantity ratio of H:L = (M − L) : (H − M).

Step-by-step calculationH : L = (6.30 − 5.70) : (7.20 − 6.30)= 0.60 : 0.90 = 2 : 3

Common pitfallsInverting the ratio. Remember H:L corresponds to (M − L):(H − M), not vice versa.

Final Answer2 : 3 (Rs. 7.20 : Rs. 5.70)