Each bank in the town of La Rinconada has only a single set of locking

I'm responding to a PM on this one. I will start by saying the correct answer will be more logical to people who live in climates where double doors are used to maintain inside temperatures, but you can get to the answer by working through your CR process.

Assumptions fill in the logical gaps between premises and conclusions. If you want to weaken an argument you need to attack an assumption. In this question the premises state that Inverness has double doors and La Rinconada has single doors. The conclusion states that the double doors were for robbery prevention against Inverness' higher robbery rate. How do we get from double doors to robbery? We are assuming that the double doors are a method for preventing robbery (this is the logical gap between the premises and the conclusion).

Answer choices A, D, and E can quickly be eliminated for irrelevance to the issue of doors and robbery prevention. Since the correct answer is B, let's first analyze C. Choice C states that the double doors can be locked remotely. That seems to strengthen the assumption that the double doors are for robbery prevention. That choice feels very relevant to the argument but it's relevant in the wrong direction. We are trying to weaken the argument so we have to attack the assumption that doors are for robbery prevention, not strengthen it.

That only leaves us with choice B. Again, I will admit this requires a bit of a mental stretch for some, but can you think of the impact that climate has on door selection or use? Sure, when it's warm I sometimes leave my door open, but when it's cold or stormy I will absolutely close my door. This choice does provide information to suggest that the double doors may not have been installed for robbery prevention and instead as a protection against climate.

Don't be too quick to call some answer choices like this one out of scope. These questions can introduce new information not previously stated in the argument. The question is whether that new information attacks an assumption and therefore weakens the argument.

KW
_________________

The author assumes that the doors are installed for security purposes, B attacks this assumption. The doors are there for keeping the in-door temperature at a appropriate level.

If there are far fewer banks in Inverness than in La Rincodanca, the argument still stands.

A.Last year the number of bank robberies in La Rinconada was almost one-half greater than the corresponding figure for the previous year

The comparison is between Number of robberies in La Rinconada for last year and the year before that.
It doesnt talk about the number of robberies in Inverness.
Hence A doesn't weaken. In fact this option doesn't help us at all.

Hope the explanation helps.

[quote="pallavisatsangi"]A.Last year the number of bank robberies in La Rinconada was almost one-half greater than the corresponding figure for the previous year

The comparison is between Number of robberies in La Rinconada for last year and the year before that.
It doesnt talk about the number of robberies in Inverness.
Hence A doesn't weaken. In fact this option doesn't help us at all.

Hope the explanation helps.

Note also that the number of bank robberies isn't useful unless we know the number of banks! Twice as many bank robberies in a city with four times as many banks actually represents a city that is twice as safe.

There are plenty of reasons to rule out A), since it doesn't mention Inverness at all, but the # vs. % error is a classic issue that shows up on the GMAT again and again--keep your eyes out for that pattern!

answer sgould be c.

it gives an alternate reason to why there is a 2 lock system.

b is no way the correct answer.

Each bank in the town of La Rinconada has only a single set of locking doors at its entrance. In the town of Inverness, on the other hand, the entrances to nearly all banks are equipped with two sets of locking doors, operated by a mechanism that allows only one set of doors to be open at a time. It is clear, then, that banks in Inverness experience more robbery attempts than do those in La Rinconada, and have thus adopted the extra doors as a security measure.

Which of the following, if true, most weakens the argument above?

a) Last year the number of bank robberies in La Rinconada was almost one-half greater than the corresponding figure for the previous year. Incorrect - does not talk anything about the town of Inverness.
b) Inverness is known for its harsh winters, while the climate of La Rinconada is quite temperate year-round. Correct - Inverness banks have two doors to manage the temperature inside the bank and they are not specifically meant to control robbery. It has a direct effect on the conclusion.
c) The mechanism of the double doors used by banks in Inverness allows bank security personnel to lock the doors remotely. Incorrect - looks like the answer but not. Although it looks like an alternative reason, locking remotely or manually does not matter. The point does not weaken the conclusion.
d) Bank robbery attempts are typically unsuccessful, and, even when the robbers do manage to escape with stolen money, the sum is usually quite small. Incorrect - does not weaken. sum of money does not matter.
e) Inverness has almost twice as many police officers per capita as does La Rinconada. Incorrect - number of police officers does not affect the conclusion.

b) Inverness is known for its harsh winters, while the climate of La Rinconada is quite temperate year-round.
c) The mechanism of the double doors used by banks in Inverness allows bank security personnel to lock the doors remotely.

This is not a good question because one has to assume a lot to mark the answer as correct one.
For b, one has already mentioned that harsh climate is the reason. What if the temperature control systems are well designed to take care of a spate of cold air entering the building when the door is opened.
For C, one can assume that a small team of security teams can manage the security of the banks by remote operation of the gates. A large number of robberies can not be the only reason behind having such 2-door systems.

B clearly is the winner.

It provides different cause than that mentioned in the Premise. The author while arriving at a conclusion believe that only 1 cause can lead to the effect. If different cause is having the same intended effect, author's conclusion will gets weakened.

I guess 'c' should be the answer. B depends again on the assumption that more number of doors help temperature to be at appropriate level, and this assumption is no where clearly stated which makes it a weak link.

Whilst in c, the reason for using 2doors is clearly stated which attacks the assumption of the author. I feel c is the answer.

If the official answer really is B, this is a terrible question. Answer choice C gives a very plausible reason why the bank set up two doors rather than just one. For B, we have to make a huge assumption that the number of door locks is directly related to the quality of weather control inside a bank.

The point here is that the conclusion says that the double- door system is a security measure. We need to weaken this thinking. So, any choice that augments the security aspect is irrelevant. We need to look a totally different reason other than security against robbery or any such things. Therefore, B simply weighs in. We can ignore C, because it strengthens the argument that extra security measures are required in the second town
B is the correct choice
_________________

For answer B, climate may explain why a two-door system is desirable, but it does nothing to explain why a double-locking system is desirable. Even if B is true, Inverness banks still have twice as many locks on their doors as do La Rinconada banks. So I'm not sure how B weakens the argument that Inverness banks have greater security concerns than do La Rinconada banks.

After all, the argument isn't saying "Inverness banks have two doors and La Rinconada banks only have one. Therefore Inverness banks have greater security concerns than La Rinconada banks". That would be a ridiculous argument, since it's pretty easy to walk through a door. The argument is based specifically on the fact that Inverness banks have two *locked* doors. The right answer to this question absolutely needs to address that point.

But answer C is the only other remotely plausible candidate, and to even contemplate C, I need to start making a lot of assumptions about bank security protocols. Making certain assumptions, you might be able to claim that C offers an alternative reason (besides additional security) for choosing double-locking doors. Perhaps remote lock operation leads to cost savings, or added convenience for bank personnel, and that's the reason Inverness banks chose them instead of single-locking doors. That seems extremely tenuous to me, though, so I dislike C as an answer here. But I think B is also quite a bad answer to this question if it is indeed the OA, since B only addresses a completely unimportant part of the original argument.
_________________

Either it is a very good question in which the correct answer wins by a margin or its really a bad one in which the correct answer makes a lot of assumptions.
_________________

I think by providing B as the answer, the question maker somewhat assumes people understand how climate control is done in banks because the answer neither states or mentions anything such ... Could we please remove it or provide a more approachable answer?

Posted from GMAT ToolKit

OA is B with the assumption that people know why double-door system is better than single-door system in controlling temperature. Frankly, I don't know why double-door is better. Just my own opinion, this assumption is too far and is not Gmat-like. Btw, OA is OA.

Really had to think my guts out to figure this answer. "Doors used as thermostat" Who would have thought!!!

Thanks kyle for the much needed guidance.

Posted from my mobile device

I have no idea how these doors work..Though I did scratch my head over it for a while(I knew this was the answer..MGMAT is too predictable on such weird options)
'One should not apply external knowledge on CR and RC questions' is the most basic rule in solving these
Secondly,
For C, the remote locking system makes sense if you think that banks in city I are just plain techsavy (which is again an assumption...but what is not )
For B, it needs external info & without that knowledge it is just a sentence that has no effect on the question