ratio

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ratio

by alltimeacheiver » Fri May 13, 2011 4:41 am
why not b. It is clear at one sight.. pls share ur input
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by MAAJ » Fri May 13, 2011 5:25 am
alltimeacheiver wrote:why not b. It is clear at one sight.. pls share ur input
Can you please copy the problem? I can't see the .PNG :(....
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by Whitney Garner » Sat May 14, 2011 5:23 am
alltimeacheiver wrote:why not b. It is clear at one sight.. pls share ur input
If a certain company purchased computers at $2,000 each and printers at $300 each, how many computers did it purchase?

(1) More than three printers were purchased.
(2) The total amount for the purchase of the computers and the printers was $15,000.
Statement (1);
Says nothing about computers

Statement (2):
From the stem we know that the total purchase of computers and printers can be expressed as:

2000c + 300p

From this statement, we know that sum will be $15,000, so:

15000 = 2000c + 300p

This is a single expression with TWO variables so it is unlikely to give us a unique (integer) value for both of our variables, but we can see what pairs would work:

First we check the high priced item, Computers.

0 comp = 0 (15,000 left for printers = 50 printers)
1 comp = 2,000 (13,000 left for printers = NOT WHOLE # of printers)
2 comps = 4,000 (11,000 left for printers = NOT WHOLE # of printers)
3 comps = 6,000 (9,000 left for printers = 30 printers)
4 comps = 8,000 (7,000 left for printers = NOT WHOLE # of printers)
5 comps = 10,000 (5,000 left for printers = NOT WHOLE # of printers)
6 comps = 12,000 (3,000 left for printers = 10 printers)
7 comps = 14,000 (1,000 left for printers = NOT WHOLE # of printers)
8 comps = TOO MUCH

So statement (2) gives 3 possible outcomes:
- 0 computers and 50 printers
- 3 computers and 30 printers
- 6 computers and 10 printers


Statement (1+2)
We have not eliminated any of the possible scenarios from statement (1) because in ALL cases more than 3 printers were purchased.

The correct answer is E

:)
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by Nina1987 » Fri Jan 15, 2016 6:25 am
It's not b as the LCM of 2000 and 300 is less than 15,000. This is the reason the equation will not form a Diophantine equation and will not result in a unique solution.

I think my logic is sound. But expert opinion will be much appreciated. thanks

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by [email protected] » Fri Jan 15, 2016 10:36 am
Hi Nina1987,

You are correct - the correct answer is NOT B. Answer B is what the original poster chose when he/she originally answered the question and took the screen-grab.

Whitney Garner's post includes the correct answer.

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by Nina1987 » Fri Jan 15, 2016 9:03 pm
Thanks for your reply Rich. However, I know that the OA is E. What I was asking was 'if my reason for ruling out B is right?' Again my reason was- "the LCM of 2000 and 300 is less than 15,000. This is the reason the equation will not form a Diophantine equation and will not result in a unique solution."
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by [email protected] » Sat Jan 16, 2016 10:48 am
Hi Nina1987,

The fact that the LCM is less than 15,000 is NOT enough of a reason to state that Fact 2 is INSUFFICIENT. You ultimately have to prove that there is more than one answer to the given prompt and you technically have not done that yet.

Here, since computers cost $2,000 each and printers cost $300 each, there are multiple ways to get to a total of $15,000

We could have....
6 computers and 10 printers (so the answer to the question is 6)
3 computers and 30 printers (so the answer to the question is 3)

Those two different results are WHY Fact 2 is INSUFFICIENT.

Logically, your instincts were correct, but DS questions sometimes have subtle 'design elements' that punish Test Takers who are not thorough enough in their thinking. If you have an idea about whether a particular Fact is sufficient or insufficient, then you should be able to PROVE that you're correct. That proof is what you'll need to guarantee the high Score that you're after.

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by Mo2men » Mon Sep 05, 2016 2:33 pm
[email protected] wrote:Hi Nina1987,

The fact that the LCM is less than 15,000 is NOT enough of a reason to state that Fact 2 is INSUFFICIENT. You ultimately have to prove that there is more than one answer to the given prompt and you technically have not done that yet.

Here, since computers cost $2,000 each and printers cost $300 each, there are multiple ways to get to a total of $15,000

We could have....
6 computers and 10 printers (so the answer to the question is 6)
3 computers and 30 printers (so the answer to the question is 3)

Those two different results are WHY Fact 2 is INSUFFICIENT.

Logically, your instincts were correct, but DS questions sometimes have subtle 'design elements' that punish Test Takers who are not thorough enough in their thinking. If you have an idea about whether a particular Fact is sufficient or insufficient, then you should be able to PROVE that you're correct. That proof is what you'll need to guarantee the high Score that you're after.

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Hi Rich,

I have another way to establish a shortcut yet based on logic and math for Fact 2

Fact 2 could be simplified to the equation: 20C + 3P = 150

It means that we need a number that, when added up, gives a number with unit digit 0. This happened only if we have either 2 numbers with unit digits (5,5) or 2 numbers with unit digits (0,0. Second case is our case in this problem.

So our focus will be on printers part (3P) to make equal to 0 unit digit which happens only if it multiple of 10. We have limited options which could be writing down on the pad.our printers options are limited 10, 20, 30, or 40.

20C = 150 - 3 * 10= 120. C=6. True

20C = 150 - 3 * 20= 90. C=4.5 False (we need Integer)

20C = 150 - 3 * 30= 60. C=3 True and no need to check 40.

Fact 2 is sufficient.

Is my reasoning above is valid during test. Do I miss something??

Thanks

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by [email protected] » Tue Sep 06, 2016 10:15 am
Hi Mo2men,

Yes - your thinking absolutely works here. Ultimately, you can choose to organize the given information (and your work) however you choose. As long as you're doing the math correctly, and you're thorough with your work, then you can 'conceive' of the information in DS questions however you like.

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