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On Wednesday morning a fortune cookie machine ran

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On Wednesday morning a fortune cookie machine ran

by M7MBA » Fri Apr 13, 2018 5:49 am

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On Wednesday morning a fortune cookie machine ran continuously at a uniform rate to fill a production order. At what time did it completely fill the order that morning?

(1) The machine produces 300 units per hour.
(2) The machine started at 8:30 a.m.

The OA is E.

Why both statements together is not the answer? Can someone help me here? Please.
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Source: — Data Sufficiency |

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by Keith@ThePrincetonReview » Fri Apr 13, 2018 7:01 pm

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M7MBA wrote:On Wednesday morning a fortune cookie machine ran continuously at a uniform rate to fill a production order. At what time did it completely fill the order that morning?

(1) The machine produces 300 units per hour.
(2) The machine started at 8:30 a.m.

The OA is E.

Why both statements together is not the answer? Can someone help me here? Please.
Question asks for time at which machine completes the order.
Question asks for a Value, so consider what is known from the question stem. Then, consider the additional information required to answer the question.

Known: machine runs at a constant rate to fill a production order.
Needed: 1) time at which machine begins working, 2) rate at which machine works, and 3) size of production order.

Statement (1) provides only one of the three pieces of information, so write down BCE.
Statement (2) provides only one of the three pieces of information, so eliminate choice B.
Both statements together provide only two of the three pieces of information, so the correct answer is E.
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by Brent@GMATPrepNow » Mon Apr 16, 2018 9:00 am

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M7MBA wrote:On Wednesday morning a fortune cookie machine ran continuously at a uniform rate to fill a production order. At what time did it completely fill the order that morning?

(1) The machine produces 300 units per hour.
(2) The machine started at 8:30 a.m.

Target question: At what time did it completely fill the order that morning?
For this work question, we need to know that time = (output)/(rate)

Statement 1: The machine produces 300 units per hour.
Okay, so we know the machine's rate, but we don't know anything about the size of the production order (aka output)
As such, statement 1 is NOT SUFFICIENT

Statement 2: The machine started at 8:30 a.m.
This doesn't help us at all.
We don't know the machine's rate AND we don't know the size of the production order (output).
So, statement 2 is NOT SUFFICIENT

Statements 1 and 2 combined
Notice that, even when we COMBINE the statements, we still don't know anything about the size of the production order.
As you can imagine, the size of the order will change to time at which the order is filled.
If you're not convinced, consider these two possible cases :
Case a: The production order consists of 300 fortune cookies. This means the time to complete the order = (300 cookies)/(300 cookies per hour) = 1 hour. The machine started at 8:30 a.m., so 1 hour later (at 9:30 am), the machine will have filled the order. So, the answer to the target question is 9:30 am
Case b: The production order consists of 3000 fortune cookies. This means the time to complete the order = (3000 cookies)/(300 cookies per hour) = 10 hours. The machine started at 8:30 a.m., so 10 hours later (at 6:30 pm), the machine will have filled the order. So, the answer to the target question is 6:30 pm
Since we cannot answer the target question with certainty, the combined statements are NOT SUFFICIENT

Answer: E

Cheers,
Brent
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by fskilnik@GMATH » Sun Sep 09, 2018 7:36 am

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M7MBA wrote:On Wednesday morning a fortune cookie machine ran continuously at a uniform rate to fill a production order. At what time did it completely fill the order that morning?

(1) The machine produces 300 units per hour.
(2) The machine started at 8:30 a.m.
\[?\,\,:\,\,{\text{time}}\,\,{\text{it}}\,\,{\text{finished}}\,\,{\text{the}}\,\,{\text{order}}\]
It is clear (I believe) that each statement alone is not sufficient, so let´s guarantee through a BIFURCATION (to be "shielded") even more: not even both statements together are sufficient!
\[\left( {1 + 2} \right)\,\,\,{\text{If}}\,\,\left\{ \begin{gathered}
\,{\text{order}}\,\,{\text{ = }}\,\,{\text{300}}\,\,{\text{units}}\,\,\, \Rightarrow \,\,\,? = 9:30\,\,{\text{a}}{\text{.m}}{\text{.}} \hfill \\
\,{\text{order}}\,\,{\text{ = }}\,\,{\text{600}}\,\,{\text{units}}\,\,\, \Rightarrow \,\,\,? = 10:30\,\,{\text{a}}{\text{.m}}{\text{.}} \hfill \\
\end{gathered} \right.\,\,\,\,\, \Rightarrow \,\,\,\,{\text{INSUFF}}.\]

This solution follows the notations and rationale taught in the GMATH method.

Regards,
fskilnik.
Fabio Skilnik :: GMATH method creator ( Math for the GMAT)
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