A dishonest person wants to make a profit on the selling of milk. He would like to mix water (costing nothing) with milk costing 33 $ per litre so as to make a profit of 50% on cost when he sells the resulting milk and water mixture for 36$. In what ratio should he mix the water and milk? Pick.
A) 1:20
B) 1:10
C) 3:8
D) 3:4
E) 3:2
First of all, let's consider 1 liter of the stuff he is going to sell --- naive customers think it's pure milk, but we know it's some milk-water mixture. He is going to sell this liter of milk-water for $36.   This $36 should be a 50% increase over cost. Here, we need to think about percentage increases as multipliers.   Using multipliers   (cost)*1.50 = $36   cost = 36/1.5 = 360/12 = $24   If he wants a 20% increase over cost on the sale of one liter of his milk-water, the cost has to be $24.   Well, a liter of milk costs $33, so if he is going to use just $30 of milk in his mixture, that's 24/33 = 8/11 of a liter. If milk is 8/11 of the liter, then water is 3/11 of the liter, and the ratio of water to milk is 3:8. Answer choice(3:8)
<result>C</result>
A dishonest person wants to make a profit on the selling of milk. He would like to mix water (costing nothing) with milk costing 33 $ per litre so as to make a profit of 50% on cost when he sells the resulting milk and water mixture for 36$. In what ratio should he mix the water and milk?