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How many liters of water must be evaporated from 50 liters of a 3 perc

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Joined: 02 Sep 2009
Posts: 53066
How many liters of water must be evaporated from 50 liters of a 3 perc  [#permalink]

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20 Dec 2015, 05:30
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Difficulty:

15% (low)

Question Stats:

81% (01:42) correct 19% (03:06) wrong based on 145 sessions

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How many liters of water must be evaporated from 50 liters of a 3 percent sugar solution to get a 5 percent sugar solution?

A. 2
B. 4
C. 6
D. 10
E. 20

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Re: How many liters of water must be evaporated from 50 liters of a 3 perc  [#permalink]

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20 Dec 2015, 06:03
3% sugar solution means that currently there are 1.5 Liters of sugar and this amount must be 5% of a reduced final amount (50-x)
1.5=0.05*(50-x)
0.05x=1
x=20
Asnwer E
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Joined: 20 Feb 2015
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Re: How many liters of water must be evaporated from 50 liters of a 3 perc  [#permalink]

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20 Dec 2015, 06:08
3% of sugar solution in 50 litres of water =1.5 litres
now that 1.5 litres is equal to 5% of some other solution.
which means
1.5=0.05X
x=150/5=30 Litres
thus litres of water to be evaporated =20
Manager
Joined: 24 May 2013
Posts: 79
Re: How many liters of water must be evaporated from 50 liters of a 3 perc  [#permalink]

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17 Mar 2016, 04:20
How many liters of water must be evaporated from 50 liters of a 3 percent sugar solution to get a 5 percent sugar solution?

A. 2
B. 4
C. 6
D. 10
E. 20

Sugar ----------------- solution ----------------%sugar
3/100*50=1.5----------50----------------------3
1.5-----------------------50-x---------------------5

1.5/(50-x) =5/100
x=20
Hence E.

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VP
Joined: 07 Dec 2014
Posts: 1154
Re: How many liters of water must be evaporated from 50 liters of a 3 perc  [#permalink]

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22 Dec 2017, 13:21
Bunuel wrote:
How many liters of water must be evaporated from 50 liters of a 3 percent sugar solution to get a 5 percent sugar solution?

A. 2
B. 4
C. 6
D. 10
E. 20

let x=liters of water to be evaporated
(.97*50)-x=.95(50-x)
x=20 liters
E
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Joined: 22 May 2016
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How many liters of water must be evaporated from 50 liters of a 3 perc  [#permalink]

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23 Dec 2017, 07:32
Bunuel wrote:
How many liters of water must be evaporated from 50 liters of a 3 percent sugar solution to get a 5 percent sugar solution?

A. 2
B. 4
C. 6
D. 10
E. 20

Water is zero percent sugar
Let x = amount of water evaporated

Weighted average approach:

(% sugar)(Vol) - (% sugar)(Vol) = (% sugar)(Vol)

Below, you don't have to write 0(x) on LHS, obviously.

0(x) is there to highlight that we are subtracting $$x$$ amount of evaporating water, and water is zero percent sugar -- such that volume of (50 - x) on RHS makes more intuitive sense.

$$.03(50) - 0(x) = .05(50 - x)$$
$$1.5 = 2.5 - .05x$$
$$.05x = 1$$
$$x =\frac{1}{.05}=\frac{100}{5}= 20$$

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How many liters of water must be evaporated from 50 liters of a 3 perc   [#permalink] 23 Dec 2017, 07:32
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