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A tank contains 10,000 gallons of a solution that is 5 % [#permalink]
 11 Oct 2005, 03:04
Question Stats:
83% (01:58) correct
16% (00:46) wrong based on 3 sessions
A tank contains 10,000 gallons of a solution that is 5 percent sodium chloride by volume. If 2,500 gallons of water evaporate from the tank, the remaining solution will be approximately what percent sodium chloride? (A) 1.25% (B) 3.75% (C) 6.25% (D) 6.67% (E) 11.7%
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Re: PS - Percents OG11 [#permalink]
11 Oct 2005, 03:48
nero44 wrote: I think my brain evaporated, because I dont even get any of the solutions given...
A tank contains 10,000 gallons of a solution that is 5 percent sodium chloride by volume. If 2,500 gallons of water evaporate from the tank, the remaining solution will be approximately what percent sodium chloride?
(A) 1.25%
(B) 3.75%
(C) 6.25%
(D) 6.67%
(E) 11.7%
there're 5%*10,000(= 500 gallons) of NaCl in the solution
===> there're 9,500 (=10,000-500) gallons of water in the solution.
after 2,500 gallons of water evaporate, there's 7,000 gallons of water left ===> the percentage of NaCl is 500 gallons NaCl/ (500+7,000) ( this is the volume of the solution) *100%= 6,67% . It's D.
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I got 6.67%
10000 gallons solution has
500 gallons sodium chloride
9500 gallons water
=> 2500 gallons water evaporates
=> 7000 gallons water remains
hence, concentration of sodium chloride is 500/7500 = 6.67%
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Re: PS - Percents OG11 [#permalink]
11 Oct 2005, 15:23
Should be D
Original =10,000 ----> sodium chloride = 5% ie 500
New = 10,000-2,500 = 7500.
New % = (500/7500) * 100
= 6.67%
nero44 wrote: I think my brain evaporated, because I dont even get any of the solutions given...
A tank contains 10,000 gallons of a solution that is 5 percent sodium chloride by volume. If 2,500 gallons of water evaporate from the tank, the remaining solution will be approximately what percent sodium chloride?
(A) 1.25%
(B) 3.75%
(C) 6.25%
(D) 6.67%
(E) 11.7%
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Re: A tank contains 10,000 gallons of a solution that is 5% [#permalink]
03 Mar 2012, 11:14
hi, everybody,
Sorry for raised this question again, but I a little bit confused with the question by itself.
Is that correct that if I interpret the question statement 'the remaining solution' (A) will be approximately what percent (B) 'sodium chloride'? as A=%B?
It makes me generate wrong answer!
Thanks
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Re: A tank contains 10,000 gallons of a solution that is 5% [#permalink]
03 Mar 2012, 16:45
Minhphuoc wrote: A tank contains 10,000 gallons of a solution that is 5 percent sodium chloride by volume. If 2,500 gallons of water evaporate from the tank, the remaining solution will be approximately what percent sodium chloride?
(A) 1.25%
(B) 3.75%
(C) 6.25%
(D) 6.67%
(E) 11.7%
hi, everybody,
Sorry for raised this question again, but I a little bit confused with the question by itself.
Is that correct that if I interpret the question statement 'the remaining solution' (A) will be approximately what percent (B) 'sodium chloride'? as A=%B?
It makes me generate wrong answer!
Thanks "The remaining solution will be approximately what percent sodium chloride?" means: what percent of the remaining solution is sodium chloride. Now, since the remaining solution is 10,000-2,500=7,500 gallons and sodium chloride is 500 gallons (5% of initial solution of 10,000 gallons) then sodium chloride is 500/7,500*100=~6.66% of the remaining solution of 7,500 gallons. Answer: D. Hope it's clear.
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Re: A tank contains 10,000 gallons of a solution that is 5 % [#permalink]
27 Mar 2012, 22:30
I'm really slow with math, need suggestions.
I solved this question in 2 minutes 45 seconds and got the correct answer, but obviously my time was too slow. Any suggestions for how to complete this quickly? The slowest part for me was calculating what 500/7500 is.
This was my process:
500/7500 = 5/75 = 1/15.
Long division 1/15 = 6.6% (then looked for correct answer).
Any suggestions for how to do that calculation faster (beyond just memorizing) would be great!
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Re: A tank contains 10,000 gallons of a solution that is 5 %
[#permalink]
27 Mar 2012, 22:30
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