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 40% on cost when he sells the resulting milk and water mixture for 36$. In what ratio should he mix the water and milk?
Choose the correct choice from the following answers.
A) 1:20
B) 1:10
C) 17:8
D) 17:4
E) 17:60
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 40% increase over cost. Here, we need to think about percentage increases as multipliers.   Using multipliers   (cost)*1.40 = $36   cost = 36/1.4 = 360/12 = $25.71   If he wants a 40% increase over cost on the sale of one liter of his milk-water, the cost has to be $25.71.   Well, a liter of milk costs $33, so if he is going to use just $30 of milk in his mixture, that's 25.71/33 = 60/77 of a liter. If milk is 60/77 of the liter, then water is 17/77 of the liter, and the ratio of water to milk is 17:60. Answer choice(17:60)
<result>E</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 40% on cost when he sells the resulting milk and water mixture for 36$. In what ratio should he mix the water and milk?