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A makes up 8 percent of solution R and 18 percent [#permalink]
14 Dec 2015, 06:12
Expert's post
00:00
Question Stats:
78% (01:22) correct
22% (01:44) wrong based on 50 sessions
By weight, liquid A makes up 8 percent of solution R and 18 percent of solution S. If 3 grams of solution R are mixed with 7 grams of solution S, then liquid A accounts for what percent of the weight of the resulting solution? A. 10% B. 13% C. 15% D. 19% E. 26%
Practice Questions Question: 9 Page: 152 Difficulty: medium
Re: A makes up 8 percent of solution R and 18 percent [#permalink]
14 Dec 2015, 06:19
Expert's post
Solution
Here we are mixing two solutions R and S. the percentages of A in the two solutions are 8% and 18% respectively. So the resultant mixture will also contain liquid A. and it will also depend on the weights of R and S
We can write that %A in mixture = \(\frac{(3 * 8% + 7 *18%)}{(3 +7)}\) the result is almost equal to 15%. Hence 15% is the right answer.
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Re: A makes up 8 percent of solution R and 18 percent [#permalink]
14 Jul 2016, 08:22
I chose Answer C, but it was considered wrong!
sandy wrote:
Solution
Here we are mixing two solutions R and S. the percentages of A in the two solutions are 8% and 18% respectively. So the resultant mixture will also contain liquid A. and it will also depend on the weights of R and S
We can write that %A in mixture = \(\frac{(3 * 8% + 7 *18%)}{(3 +7)}\) the result is almost equal to 15%. Hence 15% is the right answer.
Re: A makes up 8 percent of solution R and 18 percent [#permalink]
01 Aug 2016, 10:51
sandy wrote:
By weight, liquid A makes up 8 percent of solution R and 18 percent of solution S. If 3 grams of solution R are mixed with 7 grams of solution S, then liquid A accounts for what percent of the weight of the resulting solution? A. 10% B. 13% C. 15% D. 19% E. 26%
Practice Questions Question: 9 Page: 152 Difficulty: medium
Why does it shows "E" as the correct answer,whereas,it should be "C". Answer is incorrect.
Re: A makes up 8 percent of solution R and 18 percent [#permalink]
11 Feb 2019, 11:14
1
This post received KUDOS
Expert's post
sandy wrote:
By weight, liquid A makes up 8 percent of solution R and 18 percent of solution S. If 3 grams of solution R are mixed with 7 grams of solution S, then liquid A accounts for what percent of the weight of the resulting solution? A. 10% B. 13% C. 15% D. 19% E. 26%
When solving mixture questions, I often find it useful to sketch the solutions with the ingredients SEPARATED.
We have 3 grams of solution R, which is comprised of 8% liquid A So, 8% of the 3 grams will be liquid A 8% of 3 = (0.08)(3) = 0.24 So, solution R consists of 0.24 grams of liquid A
We'll now ADD 7 grams of solution S, which is comprised of 18% liquid A 18% of 7 = (0.18)(7) = 1.26 So, solution S consists of 1.26 grams of liquid A
Liquid A accounts for what percent of the weight of the resulting solution? When we combine the solutions BY PARTS, we get the following:
So, liquid A makes up 1.5 grams of the 10 grams in the resulting solution. 1.5/10 = 15/100 = 15%
Answer: C
Cheers, Brent
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Re: A makes up 8 percent of solution R and 18 percent [#permalink]
11 Feb 2019, 11:20
Expert's post
sandy wrote:
By weight, liquid A makes up 8 percent of solution R and 18 percent of solution S. If 3 grams of solution R are mixed with 7 grams of solution S, then liquid A accounts for what percent of the weight of the resulting solution? A. 10% B. 13% C. 15% D. 19% E. 26%
Another approach is to use the Weighted Averages formula:
Weighted average of groups combined = (group A proportion)(group A average) + (group B proportion)(group B average) + (group C proportion)(group C average) + ...
The weight of the resulting solution is 10 grams (3 grams + 7 grams = 10 grams)
Solution R makes up 3/10 of the resulting solution. Solution R is comprised of 8% liquid A
Solution S makes up 7/10 of the resulting solution. Solution S is comprised of 18% liquid A
Apply the formula to get: % liquid A in final solution = (3/10)(8) + (7/10)(18) = 24/10 + 126/10 = 150/10 = 15%
Answer: C
Cheers, Brent
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_________________
Brent Hanneson – Creator of greenlighttestprep.com Sign up for my free GRE Question of the Dayemails
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