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mehravikas
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 Posted: Sat Jul 12, 2008 6:04 pm Post subject: What was the yield per tree last year? |
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DS16-7 If a certain grove consists of 36 pecan trees, what was the yield per tree last year?
(1) The yield per tree for the 18 trees in the northern half of the grove was 60 kilograms last year.
(2) The yield per tree for the 18 trees in the eastern half of the grove was 55 kilograms last year.
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tzink
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| Posted: Sat Jul 12, 2008 10:14 pm Post subject: |
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Even with info from (1) and (2), we're still missing data for the southwestern quadrant of the grove, which could have any yield. If we don't know the total yield, we can't determine yield per tree.
Answer is E.
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lion147
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| Posted: Sat Jul 12, 2008 11:12 pm Post subject: |
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| tzink wrote: | Even with info from (1) and (2), we're still missing data for the southwestern quadrant of the grove, which could have any yield. If we don't know the total yield, we can't determine yield per tree.
Answer is E. |
I think it might be C.
18+18=36, so only the northern and eastern parts of the grove have trees.
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tzink
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| Posted: Sun Jul 13, 2008 8:47 am Post subject: |
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the northern half and the eastern half both have 18 trees, but they also share the northeastern quadrant. 9 trees are counted twice in the total of the northern and eastern halves. we're still missing data from the 9 trees in the southwestern quadrant.
If you draw a diagram it will help
on my diagram, red = northern half, blue = eastern half (except i wasn't thinking and put it on the left, but it doesn't matter), white = southwestern quadrant without data
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ildude02
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| Posted: Sun Jul 13, 2008 10:16 am Post subject: |
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Great explanation, tzink.
In the same context, I have one doubt with regards to these kind of problems. If a question says, a group consists of A or B and a total number of the group is given. Should we ever still consider there can be "neither of them" or we can assume there can only be A, B and may be an intersection of B that will add up to the total ?
Eg : A study group consists of Business or Spanish class students. If the total of them is 200, how many are spanish speaking.
a. Business people are 100;
b. 1/4 of businees people also go to spanish class.
If we don't need to conider neither, then I assume C would be SUFF, but I'm not sure? Also, if the question instead said, "A study group consists of Business AND Spanish class students", does AND vs OR make a difference? Appreciate your response.
| tzink wrote: | the northern half and the eastern half both have 18 trees, but they also share the northeastern quadrant. 9 trees are counted twice in the total of the northern and eastern halves. we're still missing data from the 9 trees in the southwestern quadrant.
If you draw a diagram it will help
on my diagram, red = northern half, blue = eastern half (except i wasn't thinking and put it on the left, but it doesn't matter), white = southwestern quadrant without data |
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lion147
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| Posted: Sun Jul 13, 2008 11:28 am Post subject: |
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| tzink wrote: | the northern half and the eastern half both have 18 trees, but they also share the northeastern quadrant. 9 trees are counted twice in the total of the northern and eastern halves. we're still missing data from the 9 trees in the southwestern quadrant.
If you draw a diagram it will help
on my diagram, red = northern half, blue = eastern half (except i wasn't thinking and put it on the left, but it doesn't matter), white = southwestern quadrant without data |
So with these types of problem we're to assume the quadrants overlap?
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tzink
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| Posted: Sun Jul 13, 2008 10:40 pm Post subject: |
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| lion147 wrote: | | tzink wrote: | the northern half and the eastern half both have 18 trees, but they also share the northeastern quadrant. 9 trees are counted twice in the total of the northern and eastern halves. we're still missing data from the 9 trees in the southwestern quadrant.
If you draw a diagram it will help
on my diagram, red = northern half, blue = eastern half (except i wasn't thinking and put it on the left, but it doesn't matter), white = southwestern quadrant without data |
So with these types of problem we're to assume the quadrants overlap? |
Well since it says "half" then yes. If it said "section" or "part" or anything non-quantitative, then maybe not. The half is specific enough to know that the two parts overlap.
Even with more generic terms, though, we know that we still lack the information from the southwest (or whatever remaining) portion.
I haven't done enough practice problems to know how these generally work, but that would be my thought process.
Last edited by tzink on Sun Jul 13, 2008 11:06 pm; edited 1 time in total |
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tzink
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| Posted: Sun Jul 13, 2008 10:54 pm Post subject: |
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| ildude02 wrote: | Great explanation, tzink.
In the same context, I have one doubt with regards to these kind of problems. If a question says, a group consists of A or B and a total number of the group is given. Should we ever still consider there can be "neither of them" or we can assume there can only be A, B and may be an intersection of B that will add up to the total ?
Eg : A study group consists of Business or Spanish class students. If the total of them is 200, how many are spanish speaking.
a. Business people are 100;
b. 1/4 of businees people also go to spanish class.
If we don't need to conider neither, then I assume C would be SUFF, but I'm not sure? Also, if the question instead said, "A study group consists of Business AND Spanish class students", does AND vs OR make a difference? Appreciate your response. |
Is this an actual problem or did you just come up with it for an example? Because in my understanding, the way your problem is set up it is contradictory.
Specifically, because you use "or," that means that any one student cannot both be a spanish student and a business student. Statement (2), however, says the opposite..
I think I see what you're asking though, and if we change the stem to "and," then we can explore it..
A study group consists of Business and Spanish class students. If the total of them is 200, how many are spanish speaking.
1. Business people are 100;
2. 1/4 of businees people also go to spanish class.
from (1), we only have half the data. NOT SUFFICIENT
from (2), that tells us that there is some overlap, but again, NOT SUFFICIENT
(1) and (2) together: 75 are business-only, and 25 are business/spanish. That means 100 are spanish-only. 125 total spanish speakers. SUFFICIENT
To answer your question (I think), we needn't consider the possibility that there is a student who is neither a businessperson nor a spanish speaker because of the way the stem is phrased.
If the stem was phrased differently, then it might be possible... That would be pretty dastardly of the test writers though..
Anyone with more experience know if this is done?
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mehravikas
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| Posted: Mon Jul 14, 2008 3:25 am Post subject: |
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I think, it depends on the way question is phrased. For the question posted above, we should not consider speakers who are neither business nor spanish.
Answer to my original question is 'E'.
Thanks guys.
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lion147
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| Posted: Mon Jul 14, 2008 12:06 pm Post subject: |
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| tzink wrote: | | lion147 wrote: | | tzink wrote: | the northern half and the eastern half both have 18 trees, but they also share the northeastern quadrant. 9 trees are counted twice in the total of the northern and eastern halves. we're still missing data from the 9 trees in the southwestern quadrant.
If you draw a diagram it will help
on my diagram, red = northern half, blue = eastern half (except i wasn't thinking and put it on the left, but it doesn't matter), white = southwestern quadrant without data |
So with these types of problem we're to assume the quadrants overlap? |
Well since it says "half" then yes. If it said "section" or "part" or anything non-quantitative, then maybe not. The half is specific enough to know that the two parts overlap.
Even with more generic terms, though, we know that we still lack the information from the southwest (or whatever remaining) portion.
I haven't done enough practice problems to know how these generally work, but that would be my thought process. |
I should have read the question more carefully.
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ildude02
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| Posted: Sun Jul 27, 2008 5:23 pm Post subject: |
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| tzink wrote: | | ildude02 wrote: | Great explanation, tzink.
In the same context, I have one doubt with regards to these kind of problems. If a question says, a group consists of A or B and a total number of the group is given. Should we ever still consider there can be "neither of them" or we can assume there can only be A, B and may be an intersection of B that will add up to the total ?
Eg : A study group consists of Business or Spanish class students. If the total of them is 200, how many are spanish speaking.
a. Business people are 100;
b. 1/4 of businees people also go to spanish class.
If we don't need to conider neither, then I assume C would be SUFF, but I'm not sure? Also, if the question instead said, "A study group consists of Business AND Spanish class students", does AND vs OR make a difference? Appreciate your response. |
Is this an actual problem or did you just come up with it for an example? Because in my understanding, the way your problem is set up it is contradictory.
Specifically, because you use "or," that means that any one student cannot both be a spanish student and a business student. Statement (2), however, says the opposite..
I think I see what you're asking though, and if we change the stem to "and," then we can explore it..
A study group consists of Business and Spanish class students. If the total of them is 200, how many are spanish speaking.
1. Business people are 100;
2. 1/4 of businees people also go to spanish class.
from (1), we only have half the data. NOT SUFFICIENT
from (2), that tells us that there is some overlap, but again, NOT SUFFICIENT
(1) and (2) together: 75 are business-only, and 25 are business/spanish. That means 100 are spanish-only. 125 total spanish speakers. SUFFICIENT
To answer your question (I think), we needn't consider the possibility that there is a student who is neither a businessperson nor a spanish speaker because of the way the stem is phrased.
If the stem was phrased differently, then it might be possible... That would be pretty dastardly of the test writers though..
Anyone with more experience know if this is done? |
Thanks for your response. I don't remember this question source, but I happen to solve it from some book and I wasn't so sure about the solution.
So, are you saying if a question there can A or B in a set. It means, that there can be NO INTERCESTION between A and B becoz it says "or" ? And is the intersection ONLY possible if a question states that a set consists of A and B ? Appreciate your response.
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