I think, we've all seen the accidentally doubling a portion of a mixture problem. Is there a way to do them without making up numbers?
Making one up:
Mixture X has A,B, and C. Recipe calls for 1/5 of A, 2/7 of B, and the remainder C. While mixing the portion of A is accidentally doubled. What percentage of the mixture is C?
Ratio
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in general two scenarios are possible: 1) keep the mixture amount unchanged 2) change the amount of mixture
strange, sometimes we eat with knife and fork - does it really matter how we eat and what we eat on GMAT
under 1)
apply smart number --> 35
A is 7, B is 5*2, C is 35-7-10
A becomes 14, C is 35-14-10
C/(A+B+C)=C/(35) or 11/35 (31%)
under 2)
apply smart number --> 35
A is 7, B is 5*2, C is 35-7-10
A becomes 14, C is 18 (still)
C/(A+A+B+C)=C/(35+7) or 18/52 (35%)
strange, sometimes we eat with knife and fork - does it really matter how we eat and what we eat on GMAT
under 1)
apply smart number --> 35
A is 7, B is 5*2, C is 35-7-10
A becomes 14, C is 35-14-10
C/(A+B+C)=C/(35) or 11/35 (31%)
under 2)
apply smart number --> 35
A is 7, B is 5*2, C is 35-7-10
A becomes 14, C is 18 (still)
C/(A+A+B+C)=C/(35+7) or 18/52 (35%)
yellowho wrote:I think, we've all seen the accidentally doubling a portion of a mixture problem. Is there a way to do them without making up numbers?
Making one up:
Mixture X has A,B, and C. Recipe calls for 1/5 of A, 2/7 of B, and the remainder C. While mixing the portion of A is accidentally doubled. What percentage of the mixture is C?
My knowledge frontiers came to evolve the GMATPill's methods - the credited study means to boost the Verbal competence. I really like their videos, especially for RC, CR and SC. You do check their study methods at https://www.gmatpill.com
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just checked the solution is identical
Tani Wolff - Kaplan wrote:A = .20X
B = .29X (approx.)
C = .51X
Total = X
Double A you get
Total = 1.20X
percentage of C = .51X/1.20X approximately 42.5%
Last edited by Night reader on Tue Mar 01, 2011 3:21 pm, edited 1 time in total.
My knowledge frontiers came to evolve the GMATPill's methods - the credited study means to boost the Verbal competence. I really like their videos, especially for RC, CR and SC. You do check their study methods at https://www.gmatpill.com
- anshumishra
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@Night readerNight reader wrote:hi Tani, doubling A we can't get 1.20x since x is responsible for B and C too
doubling the percentage violates our A-B-C ratio of three numbers in xabove it's already not .51XTani Wolff - Kaplan wrote:A = .20X
B = .29X (approx.)
C = .51X
Total = X
Double A you get
Total = 1.20X
percentage of C = .51X/1.20X approximately 42.5%
Your second method is equivalent to Tani's method (change the amount of mixture).
Tani is right.
You made a typo here : C/(A+A+B+C)=C/(35+7) or 18/52 (35%)
Otherwise the answer matches as well.
Thanks
Anshu
(Every mistake is a lesson learned )
Anshu
(Every mistake is a lesson learned )
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really? ah such nuisance , appologies Tani
anshumishra wrote:@Night readerNight reader wrote:hi Tani, doubling A we can't get 1.20x since x is responsible for B and C too
doubling the percentage violates our A-B-C ratio of three numbers in xabove it's already not .51XTani Wolff - Kaplan wrote:A = .20X
B = .29X (approx.)
C = .51X
Total = X
Double A you get
Total = 1.20X
percentage of C = .51X/1.20X approximately 42.5%
Your second method is equivalent to Tani's method (change the amount of mixture).
Tani is right.
You made a typo here : C/(A+A+B+C)=C/(35+7) or 18/52 (35%)
Otherwise the answer matches as well.
My knowledge frontiers came to evolve the GMATPill's methods - the credited study means to boost the Verbal competence. I really like their videos, especially for RC, CR and SC. You do check their study methods at https://www.gmatpill.com
- Tani
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The point of the question is that A has been doubled in violation of the original proportions and you now have to calculate the new proportions. if you doubled everything the proportions wouldn't change.
Tani Wolff