A dishonest milkman wants to make a profit on the selling of milk. He would like to mix water (costing nothing) with milk costing Rs.33 per litre so as to make a profit of 20% on cost when he sells the resulting milk and water mixture for Rs.36 In what ratio should he mix the water and milk?
(A) 1:20
(B) 1:10
(C) 1:8
(D) 1:4
(E) 6:11
dishonest milkman wants to make a profit
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I've added the phrase in red to clarify the intent of the problem:
Answer choice C: W:M = 1:8.
Cost of 1 liter of water and 8 liters of milk = (1*0) + (8*33) = 264.
Selling price of 9 liters of mixture = 9*36 = 324.
Profit/Cost = (324-264)/264 = 60/264 = 15/66 = 5/22 = more than 20%.
Incorrect: the required profit is 20%.
To REDUCE the profit, MORE MILK must be used.
Eliminate C, D and E.
Answer choice B: M:W = 1:10
Cost of 1 liter of water and 10 liters of milk = (1*0) + (10*33) = 330.
Selling price of 11 liters of mixture = 11*36 = 396.
Profit/Cost = (396-330)/330 = 66/330 = 11/55 = 1/5 = 20%.
Success!
The correct answer is B.
We can plug in the answers, which represent the ratio of water to milk.spd143 wrote:A dishonest milkman wants to make a profit on the selling of milk. He would like to mix water (costing nothing) with milk costing $33 per liter so as to make a profit of 20% on cost when he sells the resulting milk and water mixture for $36 per liter. In what ratio should he mix the water and milk?
,
(A) 1:20
(B) 1:10
(C) 1:8
(D) 1:4
(E) 6:11
Answer choice C: W:M = 1:8.
Cost of 1 liter of water and 8 liters of milk = (1*0) + (8*33) = 264.
Selling price of 9 liters of mixture = 9*36 = 324.
Profit/Cost = (324-264)/264 = 60/264 = 15/66 = 5/22 = more than 20%.
Incorrect: the required profit is 20%.
To REDUCE the profit, MORE MILK must be used.
Eliminate C, D and E.
Answer choice B: M:W = 1:10
Cost of 1 liter of water and 10 liters of milk = (1*0) + (10*33) = 330.
Selling price of 11 liters of mixture = 11*36 = 396.
Profit/Cost = (396-330)/330 = 66/330 = 11/55 = 1/5 = 20%.
Success!
The correct answer is B.
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Milkman sells at Rs. 36 a litre and makes a profit of 20 percent . His cost price is 36 x (100/120) = Rs 30
From here onwards we can use the concept of. Mixture and allegation to solve the question extremely fast.
Water. ..................................... Milk
0 Rs per litre .......................... 33 (as milk costs. Rs 33 per litre)
.......................................... 30 ( this Is the resultant when he mixes water at Rs 0 per litre and milk at 33 per litre)
.........3 ( 33-30)............................... 30 ( 30 - 0 )
Now the ratio between Water and milk is 3 : 30 . This when simplified gives a ratio of 1: 10. Hence the answer is. B.
Note Whenever two quantities are mixed to get a third quantity we can use method of mixture and allegation.
From here onwards we can use the concept of. Mixture and allegation to solve the question extremely fast.
Water. ..................................... Milk
0 Rs per litre .......................... 33 (as milk costs. Rs 33 per litre)
.......................................... 30 ( this Is the resultant when he mixes water at Rs 0 per litre and milk at 33 per litre)
.........3 ( 33-30)............................... 30 ( 30 - 0 )
Now the ratio between Water and milk is 3 : 30 . This when simplified gives a ratio of 1: 10. Hence the answer is. B.
Note Whenever two quantities are mixed to get a third quantity we can use method of mixture and allegation.
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Solution:spd143 wrote: ↑Thu Dec 19, 2013 1:02 pmA dishonest milkman wants to make a profit on the selling of milk. He would like to mix water (costing nothing) with milk costing Rs.33 per litre so as to make a profit of 20% on cost when he sells the resulting milk and water mixture for Rs.36 In what ratio should he mix the water and milk?
(A) 1:20
(B) 1:10
(C) 1:8
(D) 1:4
(E) 6:11
Let the amount of water = 1 liter and the amount of milk = x liters in the mixture. We can create the equation:
33x * 1.2 = 36(x + 1)
39.6x = 36x + 36
3.6x = 36
x = 10
We see that the ratio of water to mike in the mixture is 1 to 10.
Answer: B
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