In what ratio must water be mixed with milk to gain 16 2/3% on selling the mixture at cost price ?  Pick:
A) 1:9 B) 1:1 C) 1:2 D) 1:6 E) 1:5
Required ratio is cheaper quantity : dearer quantity = (d-m) : (m-c) Answer with Explanation: Step i) Let C.P of 1 litre of mild be Rs.1 And S.P of1 litre of mild be Rs.1 Gain = 50/3 per cent    C.P of 1 litre of mixture =                      1   3 50   100   100   x   = Re. 100 x 3/350 x 1 = 6/7 (Mean price) Step (ii) By the rule of allegation I. C.P of 1 liter of water = 0 II. C.P of 1 liter of milk = 1 III. Mean price (p) = 6/7 IV. d – m = 1 – 6/7 = 1/7 V. m – c = 6/7 - 0 = 6/7  ratio of water and milk = 1/7 : 6/7 = 1 : 6   Answer:1:6
<result>D</result>
In what ratio must water be mixed with milk to gain 16 2/3% on selling the mixture at cost price ?