Math questions from any Manhattan Prep GMAT Computer Adaptive Test.
SFguy10
 
 

Grilling steaks problem...Am I going crazy?

by SFguy10 Thu Nov 06, 2008 6:51 pm

Am I going crazy? I got the below question on a CAT exam and think that the answer would be C. I put C on the test and it marked me wrong. The CAT says the answer is E, but the CAT explinination is kind of wierd.

Can someone shed some light on this one? The way I see it is that...

QUESTION
It takes Amy between 6 and 7 minutes to grill a steak, and she can only grill one steak at a time. She does not need to take breaks between steaks. Can Amy finish grilling all the steaks needed for her party before her guests arrive?

(1) Amy needs to grill four steaks for her party.

(2) Amy's guests will arrive in half an hour.

MY THOUGHT PROCESS:
1)NOT SUFFICIENT: longest time for grilling 4 steaks is 28 mins. Know nothing about when guests are coming
2) NOT SUFFICIENT: we know when guests are coming but nothing about how many steaks.
1) and 2) together: SUFFICIENT. I thought this would be sufficient because we know from 1) Amy has 4 steaks (longest to grill 4 steaks is 28 mins) and from 2) the guests are coming in 30 mins. So, cook 4 steaks in 28 mins gives 2 mins before the guests arrive.

But, here is the explination from the exam which is confusing (where does the 25-30 mins come from?). It seems to say that 1 and 2 together are sufficient (like I answered) but then says we cannot answer the question definitively (i.e.: answer E).

(1) AND (2) SUFFICIENT: Amy will take between 24 and 28 minutes to grill the steaks and her guests will arrive in between 25 and 30 minutes, so we cannot answer the question definitively.

The correct answer is E.
upa
 
 

Re: Grilling steaks problem...Am I going crazy?

by upa Tue Nov 11, 2008 1:20 am

SFguy10 Wrote:Am I going crazy? I got the below question on a CAT exam and think that the answer would be C. I put C on the test and it marked me wrong. The CAT says the answer is E, but the CAT explinination is kind of wierd.

Can someone shed some light on this one? The way I see it is that...

QUESTION
It takes Amy between 6 and 7 minutes to grill a steak, and she can only grill one steak at a time. She does not need to take breaks between steaks. Can Amy finish grilling all the steaks needed for her party before her guests arrive?

(1) Amy needs to grill four steaks for her party.

(2) Amy's guests will arrive in half an hour.

MY THOUGHT PROCESS:
1)NOT SUFFICIENT: longest time for grilling 4 steaks is 28 mins. Know nothing about when guests are coming
2) NOT SUFFICIENT: we know when guests are coming but nothing about how many steaks.
1) and 2) together: SUFFICIENT. I thought this would be sufficient because we know from 1) Amy has 4 steaks (longest to grill 4 steaks is 28 mins) and from 2) the guests are coming in 30 mins. So, cook 4 steaks in 28 mins gives 2 mins before the guests arrive.

But, here is the explination from the exam which is confusing (where does the 25-30 mins come from?). It seems to say that 1 and 2 together are sufficient (like I answered) but then says we cannot answer the question definitively (i.e.: answer E).

(1) AND (2) SUFFICIENT: Amy will take between 24 and 28 minutes to grill the steaks and her guests will arrive in between 25 and 30 minutes, so we cannot answer the question definitively.

The correct answer is E.


C should be ok for me.
bonzie
 
 

by bonzie Wed Nov 12, 2008 10:14 am

Yes, i agree it should be E

Qs never says when Amy starts grilling...now or minutes later...
esledge
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by esledge Mon Nov 17, 2008 6:14 pm

You're not going crazy; it looks to me like the problem was changed at some point but the explanation stayed the same. I'll pass this along...thanks.

And to the last poster who wonders whether she starts grilling immediately--note that the question says "can she finish" not "will/must she finish." Thus, as long as she could finish if she did start immediately, the answer is definitely yes.
Emily Sledge
Instructor
ManhattanGMAT
mhendrix
 
 

by mhendrix Tue Nov 18, 2008 12:27 am

esledge Wrote:You're not going crazy; it looks to me like the problem was changed at some point but the explanation stayed the same. I'll pass this along...thanks.

And to the last poster who wonders whether she starts grilling immediately--note that the question says "can she finish" not "will/must she finish." Thus, as long as she could finish if she did start immediately, the answer is definitely yes.



Thanks. That's been driving me crazy!
JonathanSchneider
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Re: Grilling steaks problem...Am I going crazy?

by JonathanSchneider Thu Feb 19, 2009 2:21 pm

: )
malikrulzz
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Re: Grilling steaks problem...Am I going crazy?

by malikrulzz Thu Apr 09, 2009 8:48 am

IF it is within half hour u r not sure whether guest will arrive in 20, 25 or 30 mins
esledge
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Re: Grilling steaks problem...Am I going crazy?

by esledge Thu Apr 09, 2009 4:04 pm

malikrulzz Wrote:IF it is within half hour u r not sure whether guest will arrive in 20, 25 or 30 mins

True! But this question uses "in" not "within." On the GMAT, "in 30 minutes" should be taken to mean "in exactly 30 minutes." "Half an hour" is arguably a casual way of saying "approximately 30 minutes" in real life, but even so, "half an hour" to the GMAT would mean "exactly 0.5 hours = exactly 30 minutes."
Emily Sledge
Instructor
ManhattanGMAT