1) In what ratio must water be mixed with milk costing Rs 12 per liter to obtain mixture worth Rs 8 per litre?
1) 1:2 2) 2:1 3) 2:3 4) 3:2 4) 4:3
2) In what ratio must water be mixed with milk to gain 16 2/3 % (50/3%) on selling the mixture at the cost price?
a) 1:6 b) 6:1 c) 2:3 d) 4:3 e) none of these
3) Two vessels A and B contain spirit and water mixed in the ratio 5:2 and 7: 6 respectively. Find the ratio in which these mixtures should be mixed to obtain a new mixture in vessel C containing spirit and water in raito 8:5.
a)4:3 b) 3:4 c) 5:6 d) 7 :9 e) 9 : 11
3 Alligations and Mixtures Sums
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Hi,
1) Milk  12/lit, Water  0/lit, Mixture  8/lit.
So, Volume of water/Volume of milk = (128)/(80) = 1:2
2) Profit is (50/3)%= (50/3)/100 = 1/6. So, the volume of mixture must increase by (1/6).
So, Volume of water/Volume of milk = 1/6.
3)Fraction of spirit in A = 5/7
Fraction of spirit in B = 7/13
Fraction of spirit in C = 8/13
volume of A/volume of B = (8/137/13)/(5/78/13) = (1/13)/(9/13.7) = 7/9
Hence, D
1) Milk  12/lit, Water  0/lit, Mixture  8/lit.
So, Volume of water/Volume of milk = (128)/(80) = 1:2
2) Profit is (50/3)%= (50/3)/100 = 1/6. So, the volume of mixture must increase by (1/6).
So, Volume of water/Volume of milk = 1/6.
3)Fraction of spirit in A = 5/7
Fraction of spirit in B = 7/13
Fraction of spirit in C = 8/13
volume of A/volume of B = (8/137/13)/(5/78/13) = (1/13)/(9/13.7) = 7/9
Hence, D
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Things are not what they appear to be... nor are they otherwise
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let ratio=x:1In what ratio must water be mixed with milk costing Rs 12 per liter to obtain mixture worth Rs 8 per litre?
1) 1:2 2) 2:1 3) 2:3 4) 3:2 4) 4:3
thus water=x litre, milk=1 litre.
price = 8(1+x) = 12 (price of 1 litre milk=12)
1+x = 3/2 > x=1/2
Ratio=1:2
IMO A
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let cost price initially = 30/litre2) In what ratio must water be mixed with milk to gain 16 2/3 % (50/3%) on selling the mixture at the cost price?
a) 1:6 b) 6:1 c) 2:3 d) 4:3 e) none of these
Thus Gain 50/3% means 35/litre.
let ratio=x:1
price=(1+x)30=35 >x=1/6
thus ratio =1/6
IMO A
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a:b = 7x:13Two vessels A and B contain spirit and water mixed in the ratio 5:2 and 7: 6 respectively. Find the ratio in which these mixtures should be mixed to obtain a new mixture in vessel C containing spirit and water in raito 8:5.
a)4:3 b) 3:4 c) 5:6 d) 7 :9 e) 9 : 11
thus total spirit = 5x + 7
total water = 2x+6
(5x+7)/(2x+6) = 8/5 > 9x=13 >x=13/9
thus 7x:13 = 7:9
IMO D
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I'm curious  what's the source of these questions? I'm guessing an Indian site somewhere due to the language (and currency) used.
Be very wary of using questions that aren't worded similarly to those on the actual GMAT  you're not training yourself for real test questions. So, while the math concepts may be relevant, you may end up struggling translating the word problems you see on the exam.
Also, real GMAT questions require no assumptions at all; for example, the first question assumes that water is free (otherwise it's impossible to answer)  on the actual GMAT that would be explicitly stated. There are lots of places in the world where water isn't free (especially for industrial use).
Be very wary of using questions that aren't worded similarly to those on the actual GMAT  you're not training yourself for real test questions. So, while the math concepts may be relevant, you may end up struggling translating the word problems you see on the exam.
Also, real GMAT questions require no assumptions at all; for example, the first question assumes that water is free (otherwise it's impossible to answer)  on the actual GMAT that would be explicitly stated. There are lots of places in the world where water isn't free (especially for industrial use).
raunekk wrote:1) In what ratio must water be mixed with milk costing Rs 12 per liter to obtain mixture worth Rs 8 per litre?
1) 1:2 2) 2:1 3) 2:3 4) 3:2 4) 4:3
2) In what ratio must water be mixed with milk to gain 16 2/3 % (50/3%) on selling the mixture at the cost price?
a) 1:6 b) 6:1 c) 2:3 d) 4:3 e) none of these
3) Two vessels A and B contain spirit and water mixed in the ratio 5:2 and 7: 6 respectively. Find the ratio in which these mixtures should be mixed to obtain a new mixture in vessel C containing spirit and water in raito 8:5.
a)4:3 b) 3:4 c) 5:6 d) 7 :9 e) 9 : 11
Stuart Kovinsky  Kaplan GMAT Faculty  Toronto
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raunekk wrote:@ Frankenstein
Perfect!!
@cans
Can you explain me what is X in the 3rd one and how did u form equations using the same..
we have to find ration in which A and B should be added.Two vessels A and B contain spirit and water mixed in the ratio 5:2 and 7: 6 respectively. Find the ratio in which these mixtures should be mixed to obtain a new mixture in vessel C containing spirit and water in raito 8:5.
a)4:3 b) 3:4 c) 5:6 d) 7 :9 e) 9 : 11
a:b = 7x:13
thus total spirit = 5x + 7
total water = 2x+6
(5x+7)/(2x+6) = 8/5 > 9x=13 >x=13/9
thus 7x:13 = 7:9
IMO D
i took that ratio 7x:13 (for simplicity)
where x is any variable. i could have taken it x:1, but then calculations become a bit complex
7x:13 means 7x of A and 13 of b.
5:2 is spirit:water in A. Thus spirit = (5/7)*7x = 5x
similarly water=2x
also 7:6 is spirit:water in B. Thus spirit = (7/13)*13 = 7
water = 6
total spirit = 5x+7
total water = 2x+6
take ration and equate to 8:5
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