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?  Choose the correct choice from the following answers:
A) 36 kg  B) 42 kg  C) 54 kg  D) 63 kg  E) 30 kg
Explanation:   S.P. of 1 kg of mixture = Rs. 9.24, Gain 10%.   C.P. of 1 kg of mixture = Rs.(100/110 x 9.24)= Rs. 8.40   By the rule of allilation, we have:   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 =(7x 27 / 3)= 63 kg.   ANSWER IS 63 kg
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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?