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Must be true shipping clerk----Really Tough one.

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Must be true shipping clerk----Really Tough one.

by amysky_0205 » Sat Dec 22, 2012 7:40 pm
Shipping Clerk: The five specially ordered shipments sent out last week were sent out on Thursday. Last week, all of the shipments that were sent out on Friday consisted entirely of building supplies, and the shipping department then closed for the weekend. Four shipments were sent to Truax Construction last week, only three of which consisted of building supplies.

If the shipping clerk's statements are true, which of the following must also be true?
A. At least one of the shipments sent to Truax Construction last week was specially ordered.
B. At least one of last week's specially ordered shipments did not consist of building supplies.
C. At least one of the shipments sent to Truax Construction was not sent out on Thursday of last week.
D. At least one of the shipments that were sent out on Friday of last week was sent to Truax Construction.
E. At least one of the shipments sent to Truax Construction last week was sent out before Friday.

OA:E

can someone explain this in a more clearly way?
I can't quite understand this.....
tks
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by lunarpower » Sat Dec 22, 2012 8:58 pm
first, the good news: this kind of problem is very rare on the gmat. (on the lsat, on the other hand, this "mathematical logic" type of problem is one of the most common types.)

still, the problem is in front of us, so let's look at it.
the question asks you for a statement that "must be true", so you actually need a statement that you can PROVE -- not something to be taken lightly.
therefore, you must read the statements as exactly as possible, and then make sure to "think inside the box" when you evaluate the answer choices.

let's look at the statements. (also, keep in mind that you don't have to use every statement. you will definitely have to combine at least two of them -- GMAT CR doesn't give correct answers that are just restatements of single facts from the passage -- but you may leave some of them unused.)

1/
The five specially ordered shipments sent out last week were sent out on Thursday
--> if you are not a native speaker of english, make sure you know what "the + number" means: it means that those are the only ones.
e.g.
dave and laura were two witnesses to the crime --> there could have been many other witnesses
dave and laura were the two witnesses to the crime --> dave and laura were the only witnesses.
so, according to the statement, there were five special-order shipments on thursday, AND there were NO other special-order shipments that week.

2/
all of the shipments that were sent out on Friday consisted entirely of building supplies
--> so, if any shipment consisted of things other than building supplies, that shipment was not sent out on friday.

3/
the shipping department then closed for the weekend
--> we know there were no shipments on saturday.

4/
Four shipments were sent to Truax Construction last week, only three of which consisted of building supplies
--> this means that the fourth shipment did not consist of building supplies.
using statement #2, we know that this fourth shipment did not ship out on friday.
using statement #3, we know that it didn't ship out on saturday either.
therefore, it must have gone out before friday.
boom, (e).

note that we don't use statement #1.
(once you see the final statement, you should be able to anticipate that we probably aren't going to use #1, as we have no information about whether the truax shipments were special orders.)
Ron has been teaching various standardized tests for 20 years.

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by amysky_0205 » Sat Dec 22, 2012 10:56 pm
lunarpower wrote:first, the good news: this kind of problem is very rare on the gmat. (on the lsat, on the other hand, this "mathematical logic" type of problem is one of the most common types.)

still, the problem is in front of us, so let's look at it.
the question asks you for a statement that "must be true", so you actually need a statement that you can PROVE -- not something to be taken lightly.
therefore, you must read the statements as exactly as possible, and then make sure to "think inside the box" when you evaluate the answer choices.

let's look at the statements. (also, keep in mind that you don't have to use every statement. you will definitely have to combine at least two of them -- GMAT CR doesn't give correct answers that are just restatements of single facts from the passage -- but you may leave some of them unused.)

1/
The five specially ordered shipments sent out last week were sent out on Thursday
--> if you are not a native speaker of english, make sure you know what "the + number" means: it means that those are the only ones.
e.g.
dave and laura were two witnesses to the crime --> there could have been many other witnesses
dave and laura were the two witnesses to the crime --> dave and laura were the only witnesses.
so, according to the statement, there were five special-order shipments on thursday, AND there were NO other special-order shipments that week.

2/
all of the shipments that were sent out on Friday consisted entirely of building supplies
--> so, if any shipment consisted of things other than building supplies, that shipment was not sent out on friday.

3/
the shipping department then closed for the weekend
--> we know there were no shipments on saturday.

4/
Four shipments were sent to Truax Construction last week, only three of which consisted of building supplies
--> this means that the fourth shipment did not consist of building supplies.
using statement #2, we know that this fourth shipment did not ship out on friday.
using statement #3, we know that it didn't ship out on saturday either.
therefore, it must have gone out before friday.
boom, (e).

note that we don't use statement #1.
(once you see the final statement, you should be able to anticipate that we probably aren't going to use #1, as we have no information about whether the truax shipments were special orders.)
Hii, Ron

thank u for ur reply!

Now that i know E is the right answer, I would like to ask why D is wrong?

thank u so much!
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by lunarpower » Sat Dec 22, 2012 11:56 pm
amysky_0205 wrote:I would like to ask why D is wrong?
(d) says:
At least one of the shipments that were sent out on Friday of last week was sent to Truax Construction

there's nothing in the passage to justify this idea.
we do know that some building supplies were sent out on friday -- but there's no reason to believe that building supplies weren't also sent out earlier in the week. (compare the language of the statement about building supplies on friday with that of the statement about special orders on thursday. make sure you understand why the language of the former doesn't preclude the idea of more orders on other days, while that of the latter does.)

just as importantly, if you break down the statements line by line -- as i did above -- you should find that, if you think about what else may or may not be deduced from those statements, your thought process is already trending toward the correct answer. in that case, you may not have to think as much about process of elimination.
Ron has been teaching various standardized tests for 20 years.

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by lunarpower » Sun Dec 23, 2012 12:00 am
also, note that this whole process of breaking down the statements one by one -- as i did here -- is designed pretty much exclusively for this problem type (on which you essentially have to prove something); it may not be the greatest idea in the world on other problem types.

in other words, this sort of analysis is good for "draw your own conclusion" problems, because the answers to those problems stay strictly "inside the box" circumscribed by the statements.
on other problem types (e.g., strengthening/weakening/evaluating arguments, explaining discrepancies) -- on which the correct answers always come from outside the "box", and usually demand some sort of common-sense/real-world connection -- this type of approach is less likely to be useful, and may even compromise your ability to see the right connections.
Ron has been teaching various standardized tests for 20 years.

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Pueden hacerle preguntas a Ron en castellano
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Voit esittää kysymyksiä Ron:lle myös suomeksi

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Quand on se sent bien dans un vêtement, tout peut arriver. Un bon vêtement, c'est un passeport pour le bonheur.

Yves Saint-Laurent

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