Critical Reasoning

Kaplan Gmat Verbal workout Section 3
3.At Food World Supermarket, built in 1975, the number of successful thefts has risen dramatically in the past few months. Food World has a reliable electronic security system at all customer exit doors, and this system is always in operation.
Therefore, the thefts must have been committed by people who used exits other than the regular customer exit doors.
Which of the following is an assumption that would make the conclusion above logically
correct?
A. If a surveillance system is installed in a supermarket, it is always equipped at every possible exit.
B. If an employee so wishes, he is allowed to leave through an exit that is not monitored by surveillance equipment.
C. If a store has a reliable security system, it is impossible to pass through the system undetected.
D. If a supermarket was built before 1980, it often has exits that cannot be equipped with electronic surveillance.
E. If a store has a reliable electronic security system but is still experiencing a rise in theft it must be the case that the employees are stealing.



Who may help to explain why B is wrong and why C is correct?
"Therefore, the thefts must have been committed by people who used exits other than the regular customer exit doors" means that the theft would be caught at non-customers exit?
what is the different between" exits "and"regular customer exit door" ? are they the same exits?
the correct answer is C.

Thanks

The paragraph does not say about the fact that customers cannot use doors other than customer exit doors. Also, b, suggests that the employees are the culprit there is no trace of such suggestion in the paragraph.

There are certain pieces which are not mentioned in the text.
Firstly, who all can exit via doors that are not regular customer exits. It might be customers or employees. How can you assume or conclude that no customer can exit via that except employees. So the assumption that it has to be an employee is wrong.

Hence Option C holds on. Hope that helped.

graceguo98 wrote:Kaplan Gmat Verbal workout Section 3
3.At Food World Supermarket, built in 1975, the number of successful thefts has risen dramatically in the past few months. Food World has a reliable electronic security system at all customer exit doors, and this system is always in operation.
Therefore, the thefts must have been committed by people who used exits other than the regular customer exit doors.
Which of the following is an assumption that would make the conclusion above logically
correct?
A. If a surveillance system is installed in a supermarket, it is always equipped at every possible exit.
B. If an employee so wishes, he is allowed to leave through an exit that is not monitored by surveillance equipment.
C. If a store has a reliable security system, it is impossible to pass through the system undetected.
D. If a supermarket was built before 1980, it often has exits that cannot be equipped with electronic surveillance.
E. If a store has a reliable electronic security system but is still experiencing a rise in theft it must be the case that the employees are stealing.



Who may help to explain why B is wrong and why C is correct?
"Therefore, the thefts must have been committed by people who used exits other than the regular customer exit doors" means that the theft would be caught at non-customers exit?
what is the different between" exits "and"regular customer exit door" ? are they the same exits?
the correct answer is C.

Thanks

I was able to find C to be the correct answer. This is my accumalitive experience with assumptions and weakeners:

I noticed that the CR Bible says to focus on the cause and effect in the conclusion, which in this case are other exits and more crime respectively. However, I noticed that this is not always the case. about 2/3 of the questions look for an assumption in the premises that help to reach the conclusion. For example, in some assumption questions it asks to find the assumption on which the conclusion depends.
In this question, if he did not assume that the dectors work, the conclusion could have been that theft is due to something wrong with the alarm detectors.

Hope that helps, cheers