MGMAT qn - cake refrigerator

[kiran99x]

I came across this question in the mgmat question bank.


Normally it takes a week for a cake to become moldy in a refrigerator. The cake in Alex's refrigerator is moldy. Therefore, the cake in Alex's refrigerator must be at least a week old.

Which of the following, if true, strengthens the conclusion?

A. Alex's refrigerator has not been cleaned in two years.

B. A blown fuse in Alex's building has deprived his refrigerator of electricity for the past five days.

C.The cake had just been baked when it was placed in Alex's refrigerator; it has remained there ever since.

D. A recent study demonstrated that 95% of refrigerators currently in use will keep a cake fresh for one week.

E.The cake was baked on a Tuesday.

I chose the answer D because I concluded that no other choice strengthened the conclusion. The OA is C. The explanation is that the cake could have been kept outside for some time before keeping it in the refrigerator. I can't fully understand this explanation because the premise does not bring out that the cake should be freshly baked for it to remain in the refrigerator for a week. The premise can mean that any cake kept in the refrigerator can last for a week before it gets spoiled ??

I would like to know how to tackle such questions.

[patelbhavesh_09]

I came across this question in the mgmat question bank.


Normally it takes a week for a cake to become moldy in a refrigerator. The cake in Alex's refrigerator is moldy. Therefore, the cake in Alex's refrigerator must be at least a week old.

Which of the following, if true, strengthens the conclusion?

A. Alex's refrigerator has not been cleaned in two years.

B. A blown fuse in Alex's building has deprived his refrigerator of electricity for the past five days.

C.The cake had just been baked when it was placed in Alex's refrigerator; it has remained there ever since.

D. A recent study demonstrated that 95% of refrigerators currently in use will keep a cake fresh for one week.

E.The cake was baked on a Tuesday.

I chose the answer D because I concluded that no other choice strengthened the conclusion. The OA is C. The explanation is that the cake could have been kept outside for some time before keeping it in the refrigerator. I can't fully understand this explanation because the premise does not bring out that the cake should be freshly baked for it to remain in the refrigerator for a week. The premise can mean that any cake kept in the refrigerator can last for a week before it gets spoiled ??

I would like to know how to tackle such questions.

Kiran,

Just like your previous quesiton, try here to find flaw of the argument.
"what if cake kept outside for some time before keeping it in the refrigerator?"

Option C is just doing that. It fixes the gap.

[shrikantbhaiya]

Kiran,

You are right that nothing is said about keeping the fresh cake,however as soon as you read option "C" it comes to the mind. At least I thought on the same line.

Option "D" can not be the answer because what if Alex's refrigerator is in remaining 5%. We don't know about it. We don't know anything about in which % the Alex's refrigerator will fall.
Option "A","B" and "E" are out of scope.

Now consider option "C".
Even after there is nothing mentioned about Fresh cake, it gives the solution that it must have spent 1 week in the refrigerator moreover it is avoiding the other possibility i.e. the Fresh Cake case.

I hope I am on right track and you got me.

Regards,
Shrikant

[ChrisB]

Hi Alex / Shrikant,

Great questions and subsequent explanations.

On answer choice C - You are correct that C highlights a gap in the logic of the argument. More specifically, the argument assumes that the cake was fresh when it went into the refrigerator. In the extreme, if the cake went into the refrigerator moldy then it clearly wouldn't need any time in the refrigerator to get moldy. In that case the conclusion is completely invalid. C strengthens the conclusion because it closes the gap in logic and makes the argument more linear:

1. Cake is freshly baked
2. Freshly baked cake goes right into refrigerator
3. Under normal conditions a cake will take 1 week to get moldy
4. We observe a moldy cake
5. We conclude the cake has been in 1 week!

Answer Choice D - D provides incomplete information that can be interpreted multiple ways. "A recent study demonstrated that 95% of refrigerators currently in use will keep a cake fresh for one week." Do the other 5% keep the cake fresh for more or less time? The answer choice doesn't tell us and the "more or less" is meaningful, because the direction will slightly strengthen or weaken the conclusion. The direction isn't provided so D has no effect on the conclusion.

As a takeaway, I'd focus on how strong or directly each answer choice makes its point. In general, if an answer choice isn't direct about its impact on the conclusion it usually is wrong. Some examples:

"Some refrigerators, if modified by the user, may be able to keep a cake fresh for months."

In this case the "if modified by the user" adds a condition to the answer choice that makes the effect of the added premise uncertain. Compare this uncertainty to the 5% above and you'll start noticing the pattern. Now compare this uncertainty to the directness of C, The cake had just been baked when it was placed in Alex's refrigerator; it has remained there ever since. The correct answer choice carries very few doubts about what happened. In general the correct answer choice will be more direct about its impact upon the argument and will contain fewer conditions than incorrect answer choices.

Thanks!
Chris