Normally it takes a week for a cake to become moldy in a refrigerator.

Question

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.

AshutoshB · Accepted Answer

This is Strengthen question, So we have to focus on the conclusion only, which is " the cake in Alex's refrigerator must be at least a week old"
  
  Prethinking:  What if the cake was placed in someone's else refrigerator for 3 days and then place in Alex's for last 2 days, in that case, it would destroy 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.  T he cake had just been baked when it was placed in Alex's refrigerator; it has remained there ever since.  :   PRETHINKING

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.

nkin · Answer

My take on why D is incorrect:

Conclusion has the word "must". So the correct option should say that in any case (100% of all times), the cake has been in the refrigerator for atleast a week.

Option D says 95% refrigerators can keep a cake fresh for a week. This means 5% refrigerators fail to keep a cake fresh for a week. This 5% does not bode well with the "must" condition and hence Option D is incorrect.

Archit3110 · Answer

Clearly D stands out over other options ;

LoneSurvivor · Answer

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?

Here author is claiming that the moldy cake was there in refrigerator at least 1 week means that the cake was not moldy initially. Option C correctly states that.

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.

sid993 · Answer

Why isn't B the answer? B says that fridge is out for past 5 days. The cake is already moldy. It takes a week to mold the cake in fridge. So, 5 days + 7 days(molding)= 12 days

mavelous · Answer

If anything, this answer makes it possible that the cake molded in fewer than 7 days.
Let's say, your fridge is of standard quality, and it was working in a standard setting without any failure. In this case your cake should be fine for a week without molding.
But if your fridge had no power for 5 days, maybe the cake went in just 3 days.

mvgkannan · Answer

Bunuel

Hi. Newbie here.

My doubt one: If we are to take conclusion, should we include the causation, if "Therefore" is used, as part of the conclusion statement. In this case, it has "Therefore, the cake in Alex's ..... "

My doubt two: "Normally" doesn't itself means say around 70-80% of the time, i.e saying equivalent to most of the times, which means it includes sometimes it doesn't happen in a week or sometimes its early, it also depends on the type of refrigerator (prethinking here).

Doubt 3:C while it says the cake was freshly baked when it was placed in the refrigerator and not touched ever since doesn't give an idea on how much time it was there inside but condition when it was kept inside and there after, D clearly moves from Normally to Almost always (95% of refrigerators keep a cake fresh for a week), so isn't it D better choice while both strengthens, but D gives clear shift from normally to almost?

Thank you. 
Regards.

Mr.B · Answer

D is wrong because it supports the premise "Normally it takes a week for a cake to become moldy in a refrigerator". It does not support logical reasoning of the argument.

Pr4n · Answer

Usually in strengthen, "must" is not necessary, but here the argument is that we are saying it is a week old. A week = 1 week , so if 95% of the refrigerators does keep it fresh for the week and 95% is a big number than why did his bread went bad in  a week.

Therefore, C is a better option choice as it both supports the premise that it takes a week for bread to get Mold, and the bread was lying there since it has been made so it must be atleast 1 week old.

harishramesh · Answer

The conclusion: Because it normally takes a week for a cake to get moldy in the fridge, if Alex's cake is moldy, it must be at least a week old.

To strengthen this, we want info that supports the cake stayed in the fridge the entire time and wasn't exposed to outside conditions that might have sped up molding.

Option C says:  the cake was fresh (just baked) when put in the fridge and has been there continuously since then. This confirms the starting point and no external factors or delays occurred.

dhairya18 · Answer

CONCLUSION: The cake in Alex's refrigerator must be at least a week old.

LINE OF REASONING:
Generalization: Normal Refrigeration Timeline -> Alex's Specific Cake Timeline
Cause-Effect: Presence of Mold -> Passage of At Least One Week

CORE ASSUMPTION: The cake experienced standard refrigeration conditions and did not begin molding prior to being placed in the refrigerator.

STRENGTHENING APPROACH: Confirm that no external factors accelerated the molding process, ensuring that the general "one week" timeline applies directly to this specific case.

OPTION ANALYSIS:
(A) Incorrect. An uncleaned fridge might accelerate mold growth due to excess spores, meaning the cake could be less than a week old. This weakens the argument.
(B) Incorrect. A power outage means the fridge was warm, which would cause the cake to mold faster than normal. This weakens the conclusion.
(C) Correct. This eliminates an alternative variable by confirming the cake was freshly baked when placed in the fridge and stayed there continuously. It ensures that the mold developed entirely under normal refrigeration conditions, validating the one-week timeline.
(D) Incorrect. This mildly supports the premise that cakes normally last a week in a fridge. However, we already accept the prompt's premises as fact. It does nothing to secure the timeline of Alex's specific cake.
(E) Incorrect. The specific day of the week provides no helpful data without a reference point for the current day.

Normally it takes a week for a cake to become moldy in a refrigerator.

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Normally it takes a week for a cake to become moldy in a refrigerator.

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