Shuaib has 20 ounces of 20% salt solution. How much water sh

Question

Shuaib has 20 ounces of 20% salt solution. How much water should be evaporated to make it a 30% solution?
(A) 12.67
(B) 6.67
(C) 5.67
(D) 10
(E) none of these

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CrackverbalGMAT · Accepted Answer

Shuaib has 20 ounces of 20% salt solution. How much water should be evaporated to make it a 30% solution?

We have 20 ounce salt solution with 20% salt in it.

Amount of Salt in the solution = 20 % of 20 = 4 ounces

Let X be the solution left, after evaporation. 
** Note:
 The Salt content in the solution ,after evaporation will be the same as before . Only water will get evaporated during the process but the salt concentration will increase accordingly.

Percentage of Salt has changed from 20 % to 30 %

30% of X = 4

X = 4*100/30 = 40/3 = 13.33 ounces

Amount of water evaporated = 20 - 13.33 = 6.67 ounces

Option B is the answer.

Thanks,
  Clifin J Francis,
GMAT SME

chetan2u · Answer

Which item remains constant as water evaporates : salt.

Now, salt is 20% of 20 ounces or 4 ounces. 
Thus 4 ounces is 30% of new solution =>  4=\frac{30x}{100}………x=\frac{40}{3}=13.33

So, qty of water that gets evaporated = 20-13.33=6.67

B

Crytiocanalyst · Answer

20x+ 80x = 20 
=> x=0.2

let 80 y be the amount of water to be evaporated then

20x / 20X + 80 (x-y) = 30 /100
=> 4/ 20 -80y = 3/10 
=> y=12

Therefore 80/12 = 6.67 therefore IMO B

Maria240895chile · Answer

\frac{4}{20-x}=\frac{3}{10}

40=60-3x
X=20/3
X=6,67

20% of 20 is 4. Because the quantity we need to take off is just water, we substract the amount X only from the denominator. Then equal to 30% which is equal to 3/10

_sibs_41 · Answer

Let, y be the amount of water evaporated
16-y=0.7 (20-y)
or, 16-y=14-0.7y
or, 0.3y=2
or, y=2/0.3
So, y=6.67

laborumpossimus · Answer

i did 
4/20-x = 30/100

40 = 60-3x
20=3x
x=20/3 
6.67

Shuaib has 20 ounces of 20% salt solution. How much water sh

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Shuaib has 20 ounces of 20% salt solution. How much water sh

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