How many kilogram of sugar costing Rs. 9 per kg must be mixed with 27 kg of sugar costing Rs. 7 per kg so that there may be a gain of 10% by selling the mixture at Rs. 9.24 per kg?

• A. 42 kg
• B. 36 kg
• C. 63 kg
• D. 54 kg

Answer: (C)

S.P. of 1 kg of mixture = Rs. 9.24, Gain 10%. ∴ C.P. of 1 kg of mixture = Rs. ❨ 100 x 9.24 ❩ = Rs. 8.40 110 By the rule of allilation, we have: C.P. of 1 kg sugar of 1st kind Cost of 1 kg sugar of 2nd kind Rs. 9 Mean Price Rs. 8.40 Rs. 7 1.40 0.60 ∴ Ratio of quantities of 1st and 2nd kind = 14 : 6 = 7 : 3. Let x kg of sugar of 1st be mixed with 27 kg of 2nd kind. Then, 7 : 3 = x : 27 ⟹ x = ❨ 7 x 27 ❩ = 63 kg.