In what proportion must rice at Rs 3.10 per kg be mixed with rice at Rs 3.60 per kg, so that the mixture be worth Rs 3.25 a kg?  Pick one.
A) 3/5 B) 3/2 C) 5/3 D) 5/7 E) 7/3
C.P of 1 kg of cheaper rice = Rs 3.10   C.P of 1 kg of expensive rice = Rs 3.60   the mixture be worth for 1 kg = Rs 3.25   By the alligation rule : Quantity of cheaper rice / Quantity of expensive rice   = (3.6 - 3.25)/(3.25 - 3.10)   = (0.35)/(0.15)   = 7/3   7/3
<result>E</result>
In what proportion must rice at Rs 3.10 per kg be mixed with rice at Rs 3.60 per kg, so that the mixture be worth Rs 3.25 a kg?