How many kilograms 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) 33
B) 39
C) 38
D) 63
E) 01
By the rule of alligation:   C.P. of 1 kg sugar of 1st kind C.P. of 1 kg sugar of 2nd kind   {\color{Blue} \therefore } Ratio of quantities of 1st and 2nd kind = 14 : 6 = 7 : 3.   Let x kg of sugar of 1st kind be mixed with 27 kg of 2nd kind.   Then, 7 : 3 = x : 27 or x = (7 x 27 / 3) = 63 kg.   Answer: 63) 63 Kg
<result>D</result>
How many kilograms 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 ?