1.  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? 

Answer: Option D Explanation:
S.P. of 1 kg of mixture = Rs. 9.24, Gain 10%.
By the rule of allilation, we have:
Ratio of quantities of 1^{st} and 2^{nd} kind = 14 : 6 = 7 : 3. Let x kg of sugar of 1^{st} be mixed with 27 kg of 2^{nd} kind. Then, 7 : 3 = x : 27
