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?
Pick.
A) 36 kg  B) 42 kg  C) 54 kg  D) 63 kg  E) 60 kg
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   C.P. of 1 kg sugar of 1st kind Rs.9   Cost of 1 kg sugar of 2nd kind Rs.7   Mean Price Rs. 8.40   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)/3	= 63 kg.   Answer: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?